Close Cassini flybys of Saturn’s ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus

Saturn’s main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. Data on the moons’ morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. We find that the optical properties of the moons’ surfaces are determined by two competing processes: contamination by a red material formed in Saturn’s main ring system and accretion of bright icy particles or water vapor from volcanic plumes originating on the moon Enceladus.

Spectral properties of Titan's impact craters imply chemical weathering of its surface

We examined the spectral properties of a selection of Titan's impact craters that represent a range of degradation states. The most degraded craters have rims and ejecta blankets with spectral characteristics that suggest that they are more enriched in water ice than the rims and ejecta blankets of the freshest craters on Titan. The progression is consistent with the chemical weathering of Titan's surface. We propose an evolutionary sequence such that Titan's craters expose an intimate mixture of water ice and organic materials, and chemical weathering by methane rainfall removes the soluble organic materials, leaving the insoluble organics and water ice behind. These observations support the idea that fluvial processes are active in Titan's equatorial regions.

Dynamic auroral storms on Saturn as observed by the Hubble Space Telescope

We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ∼330% rigid corotation from near ∼01 h LT toward ∼08 h LT. We suggest that these are indicative of ongoing, bursty reconnection of lobe flux in the magnetotail, providing strong evidence that Saturn's auroral storms are caused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that the emission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroral form with the upward field-aligned continuity currents flowing into the associated partial ring current.

Mutational analysis reveals the FUS homolog TAF15 as a candidate gene for familial amyotrophic lateral sclerosis

FUS, EWS, and TAF15 belong to the TET family of structurally similar DNA/RNA-binding proteins. Mutations in the FUS gene have recently been discovered as a cause of familial amyotrophic lateral sclerosis (FALS). Given the structural and functional similarities between the three genes, we screened TAF15 and EWS in 263 and 94 index FALS cases, respectively. No coding variants were found in EWS, while we identified six novel changes in TAF15. Of these, two 24 bp deletions and a R388H missense variant were also found in healthy controls. A D386N substitution was shown not to segregate with the disease in the affected pedigree. A single A31T and two R395Q changes were identified in FALS cases but not in over 1,100 controls. Interestingly, one of the R395Q FALS cases also harbors a TARDBP mutation (G384R). Altogether, these results suggest that additional studies are needed to determine whether mutations in the TAF15 gene represent a cause of FALS.

Voyager 2 in the uranian system: imaging science results

Voyager 2 images of the southern hemisphere of Uranus indicate that submicrometersize haze particles and particles of a methane condensation cloud produce faint patterns in the atmosphere. The alignment of the cloud bands is similar to that of bands on Jupiter and Saturn, but the zonal winds are nearly opposite. At mid-latitudes (-70 degrees to -27 degrees ), where winds were measured, the atmosphere rotates faster than the magnetic field; however, the rotation rate of the atmosphere decreases toward the equator, so that the two probably corotate at about -20 degrees . Voyager images confirm the extremely low albedo of the ring particles. High phase angle images reveal on the order of 10(2) new ringlike features of very low optical depth and relatively high dust abundance interspersed within the main rings, as well as a broad, diffuse, low optical depth ring just inside the main rings system. Nine of the newly discovered small satellites (40 to 165 kilometers in diameter) orbit between the rings and Miranda; the tenth is within the ring system. Two of these small objects may gravitationally confine the e ring. Oberon and Umbriel have heavily cratered surfaces resembling the ancient cratered highlands of Earth's moon, although Umbriel is almost completely covered with uniform dark material, which perhaps indicates some ongoing process. Titania and Ariel show crater populations different from those on Oberon and Umbriel; these were probably generated by collisions with debris confined to their orbits. Titania and Ariel also show many extensional fault systems; Ariel shows strong evidence for the presence of extrusive material. About halfof Miranda's surface is relatively bland, old, cratered terrain. The remainder comprises three large regions of younger terrain, each rectangular to ovoid in plan, that display complex sets of parallel and intersecting scarps and ridges as well as numerous outcrops of bright and dark materials, perhaps suggesting some exotic composition.

Weber Ratio for Visual Discrimination of Velocity

As an approximation based on various experiments reported in the literature, the least detectable difference in speed (delta w) varies in direct proportion to the speed (w) over a range from 0.1 to 20 degrees of visual angle per second. The constancy of the Weber ratio (deltaw/w) aids in understanding how men react to velocity in various situations.

Tau levels do not influence human ALS or motor neuron degeneration in the SOD1G93A mouse

BACKGROUND

The microtubule-associated protein tau is thought to play a pivotal role in neurodegeneration. Mutations in the tau coding gene MAPT are a cause of frontotemporal dementia, and the H1/H1 genotype of MAPT, giving rise to higher tau expression levels, is associated with progressive supranuclear palsy, corticobasal degeneration, and Parkinson disease (PD). Furthermore, tau hyperphosphorylation and aggregation is a hallmark of Alzheimer disease (AD), and reducing endogenous tau has been reported to ameliorate cognitive impairment in a mouse model for AD. Tau hyperphosphorylation and aggregation have also been described in amyotrophic lateral sclerosis (ALS), both in human patients and in the mutant SOD1 mouse model for this disease. However, the precise role of tau in motor neuron degeneration remains uncertain.

METHODS

The possible association between ALS and the MAPT H1/H2 polymorphism was studied in 3,540 patients with ALS and 8,753 controls. Furthermore, the role of tau in the SOD1(G93A) mouse model for ALS was studied by deleting Mapt in this model.

RESULTS

The MAPT genotype of the H1/H2 polymorphism did not influence ALS susceptibility (odds ratio = 1.08 [95% confidence interval 0.99-1.18], p = 0.08) and did not affect the clinical phenotype. Lowering tau levels in the SOD1(G93A) mouse failed to delay disease onset (p = 0.302) or to increase survival (p = 0.557).

CONCLUSION

These findings suggest that the H1/H2 polymorphism in MAPT is not associated with human amyotrophic lateral sclerosis, and that lowering tau levels in the mutant SOD1 mouse does not affect the motor neuron degeneration in these animals.

Analysis of FUS gene mutation in familial amyotrophic lateral sclerosis within an Italian cohort

OBJECTIVE

Mutations in the FUS gene on chromosome 16 have been recently discovered as a cause of familial amyotrophic lateral sclerosis (FALS). This study determined the frequency and identities of FUS gene mutations in a cohort of Italian patients with FALS.

METHODS

We screened all 15 coding exons of FUS for mutations in 94 Italian patients with FALS.

RESULTS

We identified 4 distinct missense mutations in 5 patients; 2 were novel. The mutations were not present in 376 healthy Italian controls and thus are likely to be pathogenic.

CONCLUSIONS

Our results demonstrate that FUS mutations cause approximately 4% of familial amyotrophic lateral sclerosis cases in the Italian population.

A large-scale international meta-analysis of paraoxonase gene polymorphisms in sporadic ALS

BACKGROUND

Six candidate gene studies report a genetic association of DNA variants within the paraoxonase locus with sporadic amyotrophic lateral sclerosis (ALS). However, several other large studies, including five genome-wide association studies, have not duplicated this finding.

METHODS

We conducted a meta-analysis of 10 published studies and one unpublished study of the paraoxonase locus, encompassing 4,037 ALS cases and 4,609 controls, including genome-wide association data from 2,018 ALS cases and 2,425 controls.

RESULTS

The combined fixed effects odds ratio (OR) for rs662 (PON1 Q192R) was 1.09 (95% confidence interval [CI], 1.02-1.16, p = 0.01); the genotypic OR for RR homozygotes at Q192R was 1.25 (95% CI, 1.07-1.45, p = 0.0004); the combined OR for rs854560 (PON1 L55M) was 0.97 (95% CI, 0.86-1.10, p = 0.62); the OR for rs10487132 (PON2) was 1.08 (95% CI, 0.92-1.27, p = 0.35). Although the rs662 polymorphism reached a nominal level of significance, no polymorphism was significant after multiple testing correction. In the subanalysis of samples with genome-wide data from which population outliers were removed, rs662 had an OR of 1.06 (95% CI, 0.97-1.16, p = 0.22).

CONCLUSIONS

In contrast to previous positive smaller studies, our genetic meta-analysis showed no significant association of amyotrophic lateral sclerosis (ALS) with the PON locus. This is the largest meta-analysis of a candidate gene in ALS to date and the first ALS meta-analysis to include data from whole genome association studies. The findings reinforce the need for much larger and more collaborative investigations of the genetic determinants of ALS.

Mutations in the FUS/TLS gene on chromosome 16 cause familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal degenerative motor neuron disorder. Ten percent of cases are inherited; most involve unidentified genes. We report here 13 mutations in the fused in sarcoma/translated in liposarcoma (FUS/TLS) gene on chromosome 16 that were specific for familial ALS. The FUS/TLS protein binds to RNA, functions in diverse processes, and is normally located predominantly in the nucleus. In contrast, the mutant forms of FUS/TLS accumulated in the cytoplasm of neurons, a pathology that is similar to that of the gene TAR DNA-binding protein 43 (TDP43), whose mutations also cause ALS. Neuronal cytoplasmic protein aggregation and defective RNA metabolism thus appear to be common pathogenic mechanisms involved in ALS and possibly in other neurodegenerative disorders.

Optical birefringence study of the ferroelectric phase transition in lithium niobate tantalate mixed crystals: LiNb(1-x)Ta(x)O(3)

The optical birefringence of a complete solid-solution series of lithium niobate-tantalate crystals has been measured as a function of temperature. It is found that, irrespective of composition, the high-temperature paraelectric phase has a birefringence close to +0.063, suggesting that this value arises purely from the oxygen octahedra in the crystal structure. It is also observed that a small addition of lithium niobate to the tantalate produces a crystal that has zero birefringence at room temperature.

Paraoxonase 1 (PON1) organophosphate hydrolysis is not reduced in ALS

OBJECTIVE

Four recent studies report a genetic association of the paraoxonase locus with sporadic amyotrophic lateral sclerosis (ALS). We tested the hypothesis that this association correlates with functional changes in paraoxonase 1 (PON1, MIM 168820).

METHODS

Sera from 140 ALS participants; 153 age-, race-, and sex-matched controls; and 30 matched CSF samples were tested for paraoxonase, diazoxonase, and arylesterase activities. Participants with ALS were genotyped using tagging single nucleotide polymorphisms across the PON locus. Survival data and enzyme activity were correlated with genotype.

RESULTS

There was a trend toward increased paraoxonase activity in ALS compared with controls (mean control paraoxonase 701.9 +/- 469.7 U/L, mean ALS 792.5 +/- 574.1 U/L; p = 0.066 after correction) which correlated with increased frequency of the homozygous arginine (RR) variant of PON1(Q192R) (p = 0.004). There was no significant difference in PON1 protein levels, or arylesterase or diazoxonase activities. Organophosphate hydrolysis rates had no effect on ALS survival.

CONCLUSIONS

Contrary to expectations, PON1 protein, paraoxonase, diazoxonase, and arylesterase activities were not reduced in amyotrophic lateral sclerosis (ALS). The increase in PON1(R192) frequency in ALS in our study supports previous genetic susceptibility studies. Our findings suggest that the influence of PON1 polymorphisms on ALS susceptibility is not due to reduced organophosphate hydrolysis.

SOD1A4V-mediated ALS: absence of a closely linked modifier gene and origination in Asia

Familial amyotrophic lateral sclerosis (ALS) accounts for 10% of all ALS. Approximately 20% of cases are due to mutations in the Cu/Zn superoxide dismutase gene (SOD1). In North America, SOD1(A4V) is the most common SOD1 mutation. Carriers of the SOD1(A4V) mutation share a common phenotype with rapid disease progression and death on average occurring at 1.4 years (versus 3-5 years with other dominant SOD1 mutations). Previous studies of SOD1(A4V) carriers identified a common haplotype around the SOD1 locus, suggesting a common founder for most SOD1(A4V) patients. In the current study we sequenced the entire common haplotypic region around SOD1 to test the hypothesis that polymorphisms in either previously undescribed coding regions or non-coding regions around SOD1 are responsible for the more aggressive phenotype in SOD1(A4V)-mediated ALS. We narrowed the conserved region around the SOD1 gene in SOD1(A4V) ALS to 2.8Kb and identified five novel SNPs therein. None of these variants was specifically found in all SOD1(A4V) patients. It therefore appears likely that the aggressive nature of the SOD1(A4V) mutation is not a result of a modifying factor within the region around the SOD1 gene. Founder analysis estimates that the A4V mutation occurred 540 generations (approximately 12,000 years) ago (95% CI 480-700). The conserved minimal haplotype is statistically more similar to Asian than European population DNA sets, suggesting that the A4V mutation arose in native Asian-Americans who reached the Americas through the Bering Strait.

Motoneuron-specific NR3B gene: no association with ALS and evidence for a common null allele

OBJECTIVE

The GRIN3B gene encodes NR3B, a motoneuron-specific member of the NMDA type of ionotropic glutamate receptors. NR3B reduces the Ca(2+)-permeability as well as the overall current of the receptor response and may thereby protect motoneurons against glutamate-mediated excitotoxicity. We tested whether genetic dysfunction of GRIN3B is implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS).

METHODS

We searched for mutations in the GRIN3B coding region (3.1 kb) in 117 individuals with familial ALS and in 46 individuals with sporadic ALS. We genotyped the newly identified GRIN3B null allele and four "tag single nucleotide polymorphisms (SNPs)" at the GRIN3B locus in 342 individuals with sporadic ALS and in 374 matched controls. The GRIN3B null allele frequency was determined in 2,128 individuals from a worldwide panel of 42 populations. We furthermore compared the GRIN3B coding sequence in primates (human-macaque) and rodents (rat-mouse) to evaluate the molecular evolution of GRIN3B.

RESULTS

Thirty-two SNPs, including 16 previously unreported SNPs, one 27-bp deletion, a polymorphic CAG repeat, and a 4-bp insertion (insCGTT), were identified. Mutational and case-control studies did not reveal variants that cause or modify disease in ALS. Intriguing is an insCGTT variant that truncates the protein at its amino terminus and results in a GRIN3B null allele. We demonstrated a global distribution of the null allele with allele frequencies ranging between 0 and 0.38, and we delineated a null allele specific haplotype of 9.89 kb. Comparative genomic analysis across four taxa demonstrated accelerated evolution of NR3B in primates.

CONCLUSIONS

Our study supports the conclusions that 1) GRIN3B does not seem to be associated with familial or sporadic ALS, 2) the GRIN3B null allele is a common polymorphism, 3) the GRIN3B null allele has arisen once and early in human evolution, and 4) the GRIN3B gene belongs to a group of nervous system-related genes that have been subjected to faster evolution during evolution.

Genetic variability of induction and emergence times for inhalational anaesthetics

BACKGROUND AND OBJECTIVES

Anaesthetic requirements differ among inbred mouse strains. We tested the genetic influence on induction and arousal times to inhalational anaesthetics in two of these strains.

METHODS

Five male C57BL/6J (B6) and five male C3H/HeJ (C3) mice were each exposed to five different concentrations of nitrous oxide (N2O) at five different levels of halothane. Time to sleep and arousal were assessed. Data were analysed by repeated measures of analysis of variance.

RESULTS

Halothane, N2O and genetic strain, all were significant independent factors on the time to sleep, while only N2O was a significant independent factor on the time to arousal (P = 0.004). B6 mice took significantly longer to fall asleep compared to the C3 mice controlling for halothane and N2O concentrations (F-ratio = 36, P < 0.0001). The effect of N2O on time to arousal was only significant for the B6 strain (F-ratio = 10, P = 0.005), and not for the C3 strain (F-ratio = 0.8, P = 0.38).

CONCLUSIONS

Genetics influences the time to sleep for anaesthetic agents in mice.

Surface composition of Hyperion

Hyperion, Saturn's eighth largest icy satellite, is a body of irregular shape in a state of chaotic rotation. The surface is segregated into two distinct units. A spatially dominant high-albedo unit having the strong signature of H2O ice contrasts with a unit that is about a factor of four lower in albedo and is found mostly in the bottoms of cup-like craters. Here we report observations of Hyperion's surface in the ultraviolet and near-infrared spectral regions with two optical remote sensing instruments on the Cassini spacecraft at closest approach during a fly-by on 25-26 September 2005. The close fly-by afforded us the opportunity to obtain separate reflectance spectra of the high- and low-albedo surface components. The low-albedo material has spectral similarities and compositional signatures that link it with the surface of Phoebe and a hemisphere-wide superficial coating on Iapetus.

Identification of potential CSF biomarkers in ALS

BACKGROUND

The clinical diagnosis of ALS is based entirely on clinical features. Identification of biomarkers for ALS would be important for diagnosis and might also provide clues to pathogenesis.

OBJECTIVE

To determine if there is a specific protein profile in the CSF that distinguishes patients with ALS from those with purely motor peripheral neuropathy (PN) and healthy control subjects.

METHODS

CSF obtained from patients with ALS, disease controls (patients with other neurologic disorders), and normal controls were analyzed using the surface-enhanced laser desorption/ionization time-of-flight mass spectrometry proteomics technique. Biomarker sensitivity and specificity was calculated with receiver operating characteristic curve methodology. ALS biomarkers were purified and sequence identified by mass spectrometry-directed peptide sequencing.

RESULTS

In initial proteomic discovery studies, three protein species (4.8-, 6.7-, and 13.4-kDa) that were significantly lower in concentration in the CSF from patients with ALS (n = 36) than in normal controls (n = 21) were identified. A combination of three protein species (the "three-protein" model) correctly identified patients with ALS with 95% accuracy, 91% sensitivity, and 97% specificity from the controls. Independent validation studies using separate cohorts of ALS (n = 13), healthy control (n = 25), and PN (n = 7) subjects confirmed the ability of the three CSF protein species to separate patients with ALS from other diseases. Protein sequence analysis identified the 13.4-kDa protein species as cystatin C and the 4.8-kDa protein species as a peptic fragment of the neurosecretory protein VGF.

CONCLUSION

Additional application of a "three-protein" biomarker model to current diagnostic criteria may provide an objective biomarker pattern to help identify patients with ALS.

A locus on chromosome 9p confers susceptibility to ALS and frontotemporal dementia

OBJECTIVE

To perform genetic linkage analysis in a family affected with ALS and frontotemporal dementia (FTD).

METHODS

The authors performed a genome-wide linkage analysis of a four-generation, 50-member Scandinavian family in which five individuals were diagnosed with ALS and nine with FTD. Linkage calculations assuming autosomal dominant inheritance of a single neurodegenerative disease manifesting as either ALS or FTD with age-dependent penetrance were performed. Further analyses for ALS alone and FTD alone were performed. A parametric logarithm of odds (lod) score of 2.0 or greater was required for further study of a potential locus and crossover (haplotype) analysis.

RESULTS

A new ALS-FTD locus was identified between markers D9s1870 and D9s1791 on human chromosome 9p21.3-p13.3. A maximum multipoint lod score of 3.00 was obtained between markers D9s1121 and D9s2154. Crossover analysis indicates this region covers approximately 21.8 cM, or 14Mb.

CONCLUSIONS

A locus on chromosome 9p21.3-p13.3 is linked to ALS-FTD.

Effect of bronchial thermoplasty on airway distensibility

Recent studies have reported that the application of thermal energy delivered through a bronchoscope (bronchial thermoplasty) impairs the ability of airways to narrow in response to methacholine. How such altered smooth muscle affects the response of airways to lung inflation may have important clinical implications, particularly as it relates to the abnormal response of asthmatic subjects to lung inflation and deep inspiration. The aim of this study was to examine whether bronchial thermoplasty affected airway distension with lung inflation in relaxed and contracted airways. A total of 230 airways were studied, ranging 2.5-15 mm, in six dogs. These airways were divided into two groups: an untreated (control) population and a bronchial thermoplasty-treated population. Prior to treatment, the airway pressure-area curves in the two groups of airways were identical. In contrast, the relaxed and contracted airway pressure-area curves in treated airways were shifted upward at all points, showing increased airway area at both 3 and 5 weeks post-treatment. In conclusion, these results show that reducing that amount of functional smooth muscle with bronchial thermoplasty leads to increased airway size in both relaxed and contracted states over a normal range of inflation pressures.

Release of volatiles from a possible cryovolcano from near-infrared imaging of Titan

Titan is the only satellite in our Solar System with a dense atmosphere. The surface pressure is 1.5 bar (ref. 1) and, similar to the Earth, N2 is the main component of the atmosphere. Methane is the second most important component, but it is photodissociated on a timescale of 10(7) years (ref. 3). This short timescale has led to the suggestion that Titan may possess a surface or subsurface reservoir of hydrocarbons to replenish the atmosphere. Here we report near-infrared images of Titan obtained on 26 October 2004 by the Cassini spacecraft. The images show that a widespread methane ocean does not exist; subtle albedo variations instead suggest topographical variations, as would be expected for a more solid (perhaps icy) surface. We also find a circular structure approximately 30 km in diameter that does not resemble any features seen on other icy satellites. We propose that the structure is a dome formed by upwelling icy plumes that release methane into Titan's atmosphere.

Detection of serum reverse transcriptase activity in patients with ALS and unaffected blood relatives

BACKGROUND

Retroviral involvement in the etiology of sporadic ALS has been suspected for several years since the recognition that both murine and human retroviruses can cause motor neuron disease-like syndromes. In a pilot study, an increased prevalence of a retroviral marker (reverse transcriptase [RT] activity) was demonstrated in the serum of British patients with ALS. The current investigation was designed to confirm and extend these findings in a geographically distinct patient cohort under blinded testing conditions.

METHODS

A highly sensitive product-enhanced RT assay was employed to test coded sera obtained from 30 American patients with sporadic ALS and from 14 of their blood relatives, 16 of their spouses, and 28 nonrelated, nonspousal control subjects.

RESULTS

Serum RT activity was detected in a higher proportion of ALS patients (47%) than in non-blood-related controls (18%; p = 0.008). The prevalence of RT activity in the serum of spousal controls (13%) was similar to that in other non-blood-related controls. Unexpectedly, the prevalence of serum RT activity in blood relatives of ALS patients (43%) approached that in the ALS patients themselves.

CONCLUSIONS

These results confirm that patients with ALS have a significantly higher prevalence of serum reverse transcriptase (RT) activity than that seen in unrelated control subjects. The finding of a similarly increased prevalence in blood relatives of ALS patients raises the possibility that the observed RT activity might be due to an inherited endogenous retrovirus.

Simple and surprisingly effective one-step extraction-cleanup by Soxflo for DDT and its metabolites from environmental samples

A pilot study found that DDT breakdown at the GC inlet was extensive in extracts from some--but not all--samples with high organic carbon contents. However, DDT losses could be prevented with a one-step extraction-cleanup in the Soxflo instrument with dichloromethane and charcoal. This dry-column procedure took 1 h at room temperature. It was tested on spiked soil and peat samples and validated with certified soil and sediment reference materials. Spike recoveries from freshly spiked samples ranged from 79 to 111% at 20-4000 microg/kg concentrations. Recoveries from the real-world CRMs were 99.7-100.2% of DDT, 89.7-90.4% of DDD and 89.6-107.9% of DDE. It was concluded that charcoal cleanups should be used routinely during surveys for environmental DDX pollution in order to mitigate against unpredictable matrix-enhanced breakdown in the GC.

Failure to detect enterovirus in the spinal cord of ALS patients using a sensitive RT-PCR method

OBJECTIVE

To assess the association of enteroviruses (EV) with ALS by applying a sensitive seminested reverse transcription (RT) PCR protocol to the detection of enteroviral RNA in a blinded set of archived tissues from ALS and control cases.

METHODS

The specimen set consisted of 24 frozen spinal cord samples from ALS cases, 17 frozen spinal cord samples from negative control (non-ALS) cases, and 5 frozen spinal cord positive control samples. The positive controls were two human spinal cord samples spiked with poliovirus (PV) and three spinal cords from PV-infected transgenic mice. A sensitive, EV-specific, seminested RT-PCR assay was used to detect EV genome in RNA extracted from the specimens and controls.

RESULTS

The assay detected EV RNA in a 10(-5) dilution of infected mouse tissue. EV RNA was not detected in the ALS specimens or in specimens from control cases, despite the presence of amplifiable RNA as assessed by amplification with control primers, whereas all of the positive control specimens yielded the expected PV amplification product.

CONCLUSION

The reported association between EV infection and ALS was not confirmed by testing this set of specimens with these sensitive methods.

Tetanus toxin fragment C as a vector to enhance delivery of proteins to the CNS

The non-toxic neuronal binding domain of tetanus toxin (tetanus toxin fragment C, TTC) has been used as a vector to enhance delivery of potentially therapeutic proteins to motor neurons from the periphery following an intramuscular injection. The unique binding and transport properties of this 50-kDa polypeptide suggest that it might also enhance delivery of proteins to neurons after direct injection into the CNS. Using quantitative fluorimetry, we found that labeled TTC showed vastly superior retention within brain tissue after intracerebral injection compared to a control protein (bovine serum album). Fluorescence microscopy revealed that injected TTC was not retained solely in a restricted deposit along the needle track, but was distributed through gray matter in a pattern not previously described. The distribution of injected protein within the extracellular space of the gray matter and neuropil was also seen after injection of a recombinant fusion protein comprised of TTC linked to the enzyme superoxide dismutase (TTC-SOD-1). Injections of native SOD-1 in contrast showed only minimal retention of protein along the injection track. Immunohistochemistry demonstrated that both TTC and TTC-SOD-1 were distributed in a punctate perineuronal and intraneuronal pattern similar to that seen after their retrograde transport, suggesting localization primarily in synaptic boutons. This synaptic distribution was confirmed using HRP-labeled TTC with electron microscopy along with localization within neuronal endosomes. We conclude that TTC may be a useful vector to enhance neuronal delivery of potentially therapeutic enzymes or trophic factors following direct injection into the brain.

Influence of volatile anaesthetics on hypercapnoeic ventilatory responses in mice with blunted respiratory drive

BACKGROUND

Subanaesthetic concentrations of volatile anaesthetics significantly affect the respiratory response to hypoxia and hypercapnoeia. Individuals with an inherited blunted respiratory drive are more affected than normal individuals. To test the hypothesis that subjects with blunted hypercapnoeic respiratory drive are diversely affected by different anaesthetics, we studied the effects of three volatile anaesthetics on the control of breathing in C3H/HeJ (C3) mice, characterized by a blunted hypercapnoeic respiratory response.

METHODS

Using whole body plethysmography, we assessed respiratory rate (RR) and pressure amplitude in 11 male C3 mice at rest, during anaesthesia with isoflurane, sevoflurane or desflurane, and during recovery. To test respiratory drive, mice were exposed to 8% carbon dioxide. Data were analysed by two-way-analysis of variance with post hoc tests and Bonferroni correction.

RESULTS

RR was unaffected during sevoflurane anaesthesia up to 1.0 MAC. Likewise, sevoflurane at 1.5 MAC affected RR less than either isoflurane (P=0.0014) or desflurane (P=0.0048). The increased RR to a carbon dioxide challenge was blocked by all three anaesthetics even at the lowest concentration, and remained depressed during recovery (P<0.0001). Tidal volume was unaffected by all three anaesthetics.

CONCLUSIONS

In C3 mice, spontaneous ventilation was less affected during sevoflurane compared with either isoflurane or desflurane anaesthesia. However, the RR response to hypercapnoeia was abolished at 0.5 MAC for all the anaesthetic agents and remained depressed even at the end of recovery. Our data suggest that different volatile anaesthetics have varying effects on the control of breathing frequency but all block the respiratory response to carbon dioxide. Therefore, a genetic predisposition to a blunted carbon dioxide response represents a susceptibility factor that interacts with hypercapnoeic hypoventilation during maintenance of anaesthesia and in the emergence from anaesthesia, regardless of the agent used.

Wild-type nonneuronal cells extend survival of SOD1 mutant motor neurons in ALS mice

The most common inherited [correct] form of amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting adult motor neurons, is caused by dominant mutations in the ubiquitously expressed Cu-Zn superoxide dismutase (SOD1). In chimeric mice that are mixtures of normal and SOD1 mutant-expressing cells, toxicity to motor neurons is shown to require damage from mutant SOD1 acting within nonneuronal cells. Normal motor neurons in SOD1 mutant chimeras develop aspects of ALS pathology. Most important, nonneuronal cells that do not express mutant SOD1 delay degeneration and significantly extend survival of mutant-expressing motor neurons.

Heritable differences in respiratory drive and breathing pattern in mice during anaesthesia and emergence

BACKGROUND

Postanaesthetic hypoxia and ischaemia can lead to postoperative morbidity and mortality. We studied the effect of isoflurane anaesthesia in two inbred mouse strains known for phenotypic differences in breathing pattern and respiratory drive during carbon dioxide challenge and their first-generation offspring (F(1)).

METHODS

Using whole body plethysmography, we assessed respiratory rate (RR) and pressure amplitude (Amp) in male B6 (high responder to hypercapnia), C3 (low responder), and F(1) mice at rest, during anaesthesia with isoflurane, and during recovery from anaesthesia. At each time point, the magnitude and pattern of breathing were determined during hypercapnic challenge (FI(CO(2)) = 0.08). Data (mean (SD)) were analysed by generalized ANOVA with post hoc Bonferroni's correction (P<0.05).

RESULTS

During isoflurane anaesthesia, strain differences between B6 and C3 mice in RR were obscured while differences in Amp persisted. In contrast to baseline RR responses to carbon dioxide were significantly reduced at 0.5 MAC (increase in RR: 175 (33) bpm, 147 (44) bpm, 127 (33) bpm, for B6, C3, and F(1) strains respectively) and completely blocked at 1.5 MAC (change in RR: -3 (10) bpm, -2 (1) bpm, -4 (5) bpm, for B6, C3, and F(1) strains, respectively). During recovery, B6 mice showed a significant increase in RR (77 (33) bpm; P<0.0001) as well as in Amp. This was not observed in either C3 (-22 (31) bpm) or F(1) mice (23 (51) bpm).

CONCLUSION

Isoflurane anaesthesia abolished the strain differences in respiratory drive between B6, C3, and F(1) mice. However, during recovery from anaesthesia, significant strain variation in respiratory drive reappeared and was more pronounced compared with pre-anaesthetic levels. These results suggested, that genetic differences may have minimal contribution to decreased respiratory drive during anaesthesia, but may be a major risk factor for post-operative hypoventilation and the associated morbidity and mortality.

A randomized, placebo-controlled trial of topiramate in amyotrophic lateral sclerosis

OBJECTIVE

To determine if long-term topiramate therapy is safe and slows disease progression in patients with ALS.

METHODS

A double-blind, placebo-controlled, multicenter randomized clinical trial was conducted. Participants with ALS (n = 296) were randomized (2:1) to receive topiramate (maximum tolerated dose up to 800 mg/day) or placebo for 12 months. The primary outcome measure was the rate of change in upper extremity motor function as measured by the maximum voluntary isometric contraction (MVIC) strength of eight arm muscle groups. Secondary endpoints included safety and the rate of decline of forced vital capacity (FVC), grip strength, ALS functional rating scale (ALSFRS), and survival.

RESULTS

Patients treated with topiramate showed a faster decrease in arm strength (33.3%) during 12 months (0.0997 vs 0.0748 unit decline/month, p = 0.012). Topiramate did not significantly alter the decline in FVC and ALSFRS or affect survival. Topiramate was associated with an increased frequency of anorexia, depression, diarrhea, ecchymosis, nausea, kidney calculus, paresthesia, taste perversion, thinking abnormalities, weight loss, and abnormal blood clotting (pulmonary embolism and deep venous thrombosis).

CONCLUSIONS

At the dose studied, topiramate did not have a beneficial effect for patients with ALS. High-dose topiramate treatment was associated with a faster rate of decline in muscle strength as measured by MVIC and with an increased risk for several adverse events in patients with ALS. Given the lack of efficacy and large number of adverse effects, further studies of topiramate at a dose of 800 mg or maximum tolerated dose up to 800 mg/day are not warranted.

Airway response to deep inspiration: role of nitric oxide

Deep inspirations (DI) have been shown to have both bronchoprotective and bronchodilator effects in healthy subjects. The bronchodilator effects of a DI appear to be impaired in asthmatics compared with healthy subjects. This study investigated the role of nitric oxide (NO) in the bronchodilator role of a DI. In five anaesthetised and ventilated dogs, high-resolution computed tomography was used to measure the changes in airway size after a small (25 cmH2O) and large (45 cmH2O) DI before and after administering NG-nitro-L-arginine methyl ester to block NO synthesis. The depth of the inspiratory manoeuvre during a deep inspiration determined the subsequent qualitative behaviour of the airway response. Inflation to relatively high pressure resulted in airway dilation, whereas one to lower pressure leads to airway constriction. When NG-nitro-L-arginine methyl ester was administered, both a large and a small deep inspiration resulted in subsequent airway constriction. These results support the idea that nitric oxide may be a potential bronchoprotective agent in the airways.

Dysferlin mutations in Japanese Miyoshi myopathy: relationship to phenotype

OBJECTIVE

To study dysferlin gene mutations and genotype-phenotype correlations in Japanese patients with Miyoshi myopathy (MM).

BACKGROUND

MM is an autosomal recessive distal muscular dystrophy that arises from mutations in the dysferlin gene. This gene is also mutated in families with limb girdle muscular dystrophy 2B.

METHODS

The authors examined 25 Japanese patients with MM. Genomic DNA was extracted from the peripheral lymphocytes of the patients. The PCR products of each of 55 exons were screened by single strand conformation polymorphism or direct sequencing from the PCR fragments.

RESULTS

The authors identified 16 different mutations in 20 patients with MM; 10 were novel. Mutations in Japanese patients are distributed along the entire length of the gene.

CONCLUSIONS

Four mutations (C1939G, G3370T, 3746delG, and 4870delT) are relatively more prevalent in this population, accounting for 60% of the mutations in this study. This study revealed that the G3370T mutation was associated with milder forms of MM and the G3510A mutation was associated with a more severe form.

HRCT imaging of airway responsiveness: effects of anesthetics

The noninvasive imaging method, high resolution computed tomography (HRCT), has been developed in animal models and applied to humans with obstructive lung disease for assessing regional and individual airway responsiveness. The ability to directly view airway responses during provocations such as tracheal intubation in an asthmatic could greatly enhance our understanding and treatment of airway hyperresponsiveness. HRCT uses increased kilovoltage peak (kVp) and milliamperage (mAs) settings, thin slices, high spacial frequency reconstruction algorithms, and small fields of view to resolve structures as small as 200 microm. Therefore, airways as small as 1-2 mm in diameter can be viewed and measured. HRCT is a more sensitive technique for resolving airway caliber changes than clinical or research methods of pulmonary function tests. HRCT allows direct in vivo measurement of airway responsiveness to pharmacological and physiological stress that induces bronchoconstriction or bronchodilation. Using HRCT, we are able to measure airway dilation at baseline airway tone with inhalation anesthetics, differentiate the bronchodilating properties of inhalational agents in airways with tone, assess bronchodilating agents commonly used as premedications prior to anesthesia, and measure airway heterogeneity at baseline tone and their response to a variety of stimuli. This ability of HRCT to measure airway caliber and response heterogeneity in vivo noninvasively will dramatically improve our understanding of pulmonary physiology in general and the effects of anesthetics on the airways specifically.

Advantages of soxflo extractions for phytochemical analysis and bioassay screening. 1. Terpenoids

The Soxflo technique was evaluated for the rapid extraction of plant materials (<90 min) at room temperature. Qualitatively similar chromatograms were obtained by gas chromatography and thin layer chromatography (TLC) with Soxflo (SoF) and Soxhlet (SoL) extracts. Sequential solvent extractions by SoF gave slightly higher yields (132%) of five major sesquiterpenoids. TLC revealed that SoF extractions at room temperature were more selective as extracts contained compounds with a narrower range of R(f)() values. This means that the SoF technique offers the potential for one-step extractions and partial fractionation. This study also showed that there were large differences in the volatile composition of dried and fresh Piper fruits: dried fruits had predominantly sesquiterpenoids while fresh fruits had considerable quantities of both mono- and sesquiterpenoids. This is the first report of alpha-guaiene and alpha- and beta-selinene in Piper guineense fruits. It is suggested that the SoF technique can be useful for the screening of large numbers of plants for phytochemicals or for the preparation of plant extracts for subsequent bioassay studies.

Survival in transgenic ALS mice does not vary with CNS glutathione peroxidase activity

OBJECTIVE

Transgenic mice that overexpress a human gene encoding mutant cytosolic superoxide dismutase (SOD1) develop a progressive motor neuron loss that resembles human ALS. Why mutant SOD1 initiates motor neuron death is unknown. One hypothesis proposes that the mutant molecule has enhanced peroxidase activity, reducing hydrogen peroxide (H2O2) to form toxic hydroxyl adducts on critical targets. To test this hypothesis, the authors generated transgenic ALS mice with altered levels of glutathione peroxidase (GSHPx), the major soluble enzyme that detoxifies H2O2.

METHODS

SOD1(G93A) ALS mice were bred with mice bearing a murine GSHPx transgene that have a four-fold elevation in brain GSHPx levels and with mice having targeted inactivation of the GSHPx gene and reduced brain GSHPx activity.

RESULTS

Survival was not prolonged in ALS mice with elevated brain GSHPx activity (p = 0.09). ALS mice with decreased GSHPx brain activity (20% of normal) showed no acceleration of the disease course (p = 0.89). The age at disease onset in the ALS mice was unaffected by brain GSHPx activity.

CONCLUSION

The level of GSHPx activity in the CNS of transgenic ALS mice does not play a critical role in the development of motor neuron disease.

Molecular basis for hyperkalemic periodic paralysis

At least one form of periodic paralysis is a direct consequence of a mutation in a skeletal muscle, voltage-sensitive sodium channel--it was observed that many individual with this disease developed low serum potassium levels during paralytic episodes. Some families had hyperkalemic paralysis with serum potassium levels of 6 or 7 mEg/L during paralytic crises. In both hypokalemic and hyperkalemic paralysis one of the precipitants is a period of rest after exertion. In hypokalemic periodic paralysis carbohydrates may initiate weakness. In both hyper- and hypokalemic forms, the disorder is inherited as an autosomal dominant trait. During hypokalemic and hyperkalemic paralysis, one might respectively anticipate muscle hyperpolarization or depolarization. Has been observed a potassium-related abnormality of sodium conductance in the pathogenesis at least of the hyperkalemic form of periodic paralysis. The fact that TTX reverses the physiological defect suggested the hypothesis that the primary problem might be a mutation in a TTX-sensitive sodium channel. The protein consists of some 2000 amino acids with characteristic intracytoplasmic and extracellular domains as well a four remarkably conserved membrane spanning domains, each composed of six transmembrane of a polymorphism of the human sodium channel with hyperkalemic paralysis. When multipoint analysis was used to test for coinheritance of the disease with both Na-2 and growth hormone polymorphisms, a lod score of 7 was obtained. That is, the ratio of the probability of linkage to non-linkage is 10 million to one. When extracellular potassium is increased to 10 mM, the affected myotubes demonstrate strikingly abnormal channel behavior characterized by prolonged open times or repetitive opens throughout the voltage step. Potassium implicate as a primary factor triggering an abnormal sodium channel gating mode and, as a result, aberrant sodium current behavior. It was estimated that, for the normal channel, the probability of entering a non-inactivating mode was very low and independent of potassium. On the other hand, for the abnormal channel the probability of entering an inactive mode rises up to 5-fold with hyperkalemic. Four mutations have recently been detected in individuals with cold-sensitive paramyotenia congenital. Two of the cause amino acid substitutions within the III-IV intracytoplasmic loop. It is striking that one substitutes a valine for a glycine. An analysis of the molecular biology of each mutation should illuminate not only the disease phenotype but also biophysical properties of specific sub-regions of this muscle sodium channel.