Neuronal NLRP1 inflammasome activation of Caspase-1 coordinately regulates inflammatory interleukin-1-beta production and axonal degeneration-associated Caspase-6 activation.

Neuronal active Caspase-6 (Casp6) is associated with Alzheimer disease (AD), cognitive impairment, and axonal degeneration. Caspase-1 (Casp1) can activate Casp6 but the expression and functionality of Casp1-activating inflammasomes has not been well-defined in human neurons. Here, we show that primary cultures of human CNS neurons expressed functional Nod-like receptor protein 1 (NLRP1), absent in melanoma 2, and ICE protease activating factor, but not the NLRP3, inflammasome receptor components. NLRP1 neutralizing antibodies in a cell-free system, and NLRP1 siRNAs in neurons hampered stress-induced Casp1 activation. NLRP1 and Casp1 siRNAs also abolished stress-induced Casp6 activation in neurons. The functionality of the NLRP1 inflammasome in serum-deprived neurons was also demonstrated by NLRP1 siRNA-mediated inhibition of speck formation of the apoptosis-associated speck-like protein containing a caspase recruitment domain conjugated to green fluorescent protein. These results indicated a novel stress-induced intraneuronal NLRP1/Casp1/Casp6 pathway. Lipopolysaccharide induced Casp1 and Casp6 activation in wild-type mice brain cortex, but not in that of Nlrp1(-/-) and Casp1(-/-) mice. NLRP1 immunopositive neurons were increased 25- to 30-fold in AD brains compared with non-AD brains. NLRP1 immunoreactivity in these neurons co-localized with Casp6 activity. Furthermore, the NLRP1/Casp1/Casp6 pathway increased amyloid beta peptide 42 ratio in serum-deprived neurons. Therefore, CNS human neurons express functional NLRP1 inflammasomes, which activate Casp1 and subsequently Casp6, thus revealing a fundamental mechanism linking intraneuronal inflammasome activation to Casp1-generated interleukin-1-ß-mediated neuroinflammation and Casp6-mediated axonal degeneration.

Ultralong single-wall carbon nanotubes.

Since the discovery of carbon nanotubes in 1991 by Iijima, there has been great interest in creating long, continuous nanotubes for applications where their properties coupled with extended lengths will enable new technology developments. For example, ultralong nanotubes can be spun into fibres that are more than an order of magnitude stronger than any current structural material, allowing revolutionary advances in lightweight, high-strength applications. Long metallic nanotubes will enable new types of micro-electromechanical systems such as micro-electric motors, and can also act as a nanoconducting cable for wiring micro-electronic devices. Here we report the synthesis of 4-cm-long individual single-wall carbon nanotubes (SWNTs) at a high growth rate of 11 microm s(-1) by catalytic chemical vapour deposition. Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.

Formation of pile networks by long carbon nanotubes from decomposition of CO on Co-Mo film.

We report the formation of pile networks by long carbon nanotubes grown at 700 degrees C from a Co-Mo film on a quartz plate. Carbon monoxide (CO) was used as the carbon source. The networks were formed because the density of catalyst particles on the substrate was low, which resulted in low carbon nanotube density that did not support vertical growth. At the same time, the low carbon nanotube density makes it possible for CO to reach the catalysts on the substrate for continuous growth. No obvious amorphous carbon chunks were observed, suggesting that the pile networks consisted of fairly high-quality, long carbon nanotubes.

The buzz on buzz.

Word-of-mouth promotion has become an increasingly potent force, capable of catapulting products from obscurity into runaway commercial successes. Harry Potter, collapsible scooters, the Chrysler PT Cruiser, and The Blair Witch Project are all recent examples of the considerable power of buzz. Yet many top executives and marketing managers are misinformed about the phenomenon and remain enslaved to some common myths. In her article, author Renée Dye explores the truth behind these myths. Myth 1: Only outrageous or edgy products are buzz-worthy. That's simply not true. The most unlikely products, like prescription drugs, can generate tremendous buzz. Myth 2: Buzz just happens. Not so, says Dye. Buzz is increasingly the result of shrewd marketing tactics in which companies seed a vanguard group, ration supplies, use celebrity endorsements, leverage the power of lists, and initiate grassroots marketing. Myth 3: The best buzz-starters are your best customers. Often, a counterculture has a greater ability to start buzz. Myth 4: To profit from buzz, you must act first and fast. In fact, copycat companies can reap substantial profits if they know when and when not to jump in. Myth 5: The media and advertising are needed to create buzz. When used either too early or too much, the media and advertising can squelch buzz before it ignites. As globalization and brand proliferation continue, writes Dye, buzz may come to dominate the shaping of markets. Indeed, companies that are unable to control buzz may soon find the phenomenon controlling them.

Observer weighting of interaural delays in source and echo clicks.

A correlational analysis was used to assess the relative weight given to the interaural differences of time (IDTs) of source and echo clicks for echo delays ranging from 1-256 ms. In three different experimental conditions, listeners were instructed to discriminate the IDT of the source, the IDT of the echo, or the difference between the IDTs of the source and echo. The IDT of the target click was chosen randomly and independently from trial-to-trial from a Gaussian distribution (mu = 0 microsecond, sigma = 100 microseconds). The IDT of the nontarget click was either fixed at 0 microsecond or varied in the same manner as the IDT of the target. The data show that for echo delays of 8 ms or less, greater weight was given to the IDT of the source than to that of the echo in all experimental conditions. For echo delays from 16-64 ms, the IDT of the echo was weighted slightly more than that of the source and the weights accounted for a greater proportion of the responses when the echo was the target, indicating that the binaural information in the echo was dominant over the binaural information in the source. The data suggested the possibility that for echo delays from 8-32 ms, listeners were unable to resolve the temporal order of the source and echo IDTs. Listeners were able to weight the binaural information in the source and echo appropriately for a given task only when the echo delay was 128 ms or greater.

The competitive dynamics of network-based businesses.

Telecommunications carriers, transportation companies, and banks are among the many network-based businesses--companies that move people, goods, or information from various points to various other points. Managers have long assumed that customers valued all links in these networks equally. It was thought that banking customers, for example, sought access to all of the branches throughout the network or that shipping customers wanted to be able to send packages everywhere. Intuitively, managers thought that many of their customers' needs were, in reality, narrower, but they had no way of knowing which links were most important. New computing power and robust mapping software now make it possible to understand network customers better. In applying this technology, the authors, both consultants from McKinsey & Company, have uncovered three distinct usage patterns: one in which all links are, indeed, valued equally; another in which customers concentrate their use in particular zones; and a third in which customers value only individual links. Each of these patterns requires a different strategy to direct executives in making the decisions fundamental to managing any network-based business: whether to open or close outlets, whether to connect their network to others, and how to organize business units so that they reflect the network's structure. Those who don't spot the patterns or understand their strategic implications will find themselves on the losing end of the network battle.

Assembly of microtubules from tubulin bearing the nonhydrolyzable guanosine triphosphate analogue GMPPCP [guanylyl 5'-(beta, gamma-methylenediphosphonate)]: variability of growth rates and the hydrolysis of GTP.

The growth and shortening of microtubules in guanosine triphosphate-(GTP-) mediated dynamic instability has previously been observed to occur at rates which are remarkably variable (Gildersleeve et al., 1992, Chrétien et al., 1995). Neighboring microtubules observed simultaneously can grow or shorten at different rates, and a particular microtubule can undergo changes in rate with the passage of time. This paper addresses the question whether this variability has its origin in processes that involve GTP hydrolysis or whether it results from variations in the structure of microtubules that are independent of GTP hydrolysis. Tubulin was prepared with the nonhydrolyzable GTP analogue GMPPCP [guanylyl 5'-(beta, gamma-methylenediphosphonate)] bound to its exchangeable nucleotide-binding site and with GTP at its nonexchangeable site. Extensive measurements of length changes were obtained by DIC microscopy. Microtubules formed from the GMPPCP tubulin exhibited only growth. No shortening events were observed. Growth occurred at highly variable rates, indistinguishable from those exhibited by GTP tubulin. Subsequent analysis of nucleotides by high-pressure liquid chromatography (HPLC) revealed that some of the GTP that was initially present at the N-site underwent hydrolysis to produce microtubule-bound guanosine diphosphate (GDP). Despite this unexpected finding, one can conclude that variability of growth rate certainly occurs independently of dynamic instability and probably does not involve hydrolysis of GTP at the E-site.

A simulated "cocktail party" with up to three sound sources.

Listeners identified spoken words, letters, and numbers and the spatial location of these utterances in three listening conditions as a function of the number of simultaneously presented utterances. The three listening conditions were a normal listening condition, in which the sounds were presented over seven possible loudspeakers to a listener seated in a sound-deadened listening room; a one-headphone listening condition, in which a single microphone that was placed in the listening room delivered the sounds to a single headphone worn by the listener in a remote room; and a stationary KEMAR listening condition, in which binaural recordings from an acoustic manikin placed in the listening room were delivered to a listener in the remote room. The listeners were presented one, two, or three simultaneous utterances. The results show that utterance identification was better in the normal listening condition than in the one-headphone condition, with the KEMAR listening condition yielding intermediate levels of performance. However, the differences between listening in the normal and in the one-headphone conditions were much smaller when two, rather than three, utterances were presented at a time. Localization performance was good for both the normal and the KEMAR listening conditions and at chance for the one-headphone condition. The results suggest that binaural processing is probably more important for solving the "cocktail party" problem when there are more than two concurrent sound sources.

The effect of distractor frequency on judgments of target laterality based on interaural delays.

A two-dimensional stimulus-classification paradigm was used to examine the ability of listeners to judge the laterality of an interaurally delayed low-frequency target component presented concurrently with a distractor component. Of primary interest was the effect on performance of the frequency difference (Delta f) between the target and distractor. In one set of conditions, the target was fixed at 753 Hz and the distractor was 353, 553, 653, 703, 803, 853, 953, or 1153 Hz (fixed within a block of trails). In a second set of conditions, the distractor was fixed at 753 Hz and the target frequency was 353, 553, 653, 703, 803, 953, or 1153 Hz. The listeners were presented with a target component with an interaural delay that varied from trial to trial, taking on one of ten values, five leading to the left ear and five leading to the right. A distractor component was simultaneously presented with an interaural delay that also took on one of the same ten values. Delays ranged from -90 to (+)90 microseconds in 20-microsecond steps. during a block of 100 trials, each of the possible combinations of target and distractor delay was presented once and only once in a random order. Listeners were instructed to make left-right judgments based on the target delay. Each condition was repeated ten times, and the slopes of the best linear boundaries between left and right responses were used to derive the relative weights given to the target and distractor. The duration of the signals was 200 microseconds. Two of the eight listeners weighted the target heavily when the target and distractor were spectrally remote but gave the two components equal weight when the different in frequency was small. These two listeners yielded similar target weights regardless of which component was designated as the target. One listener gave nearly equal weight to the target and the distractor regardless of Delta f. Five of the listeners gave greater weight to the higher of the two frequencies regardless of which was assigned as the target. This high-frequency dominance is explained in terms of cross-correlation functions based on the composite two-tone waveforms.

The synthetic-analytic listening task for modulated signals.

The synthetic-analytic listening task (SALT) developed by Dye and colleagues [Dye et al., J. Acoust. Soc. Am. 96, 2720-2731 (1994)] was applied to a task in which an amplitude-modulated tonal carrier was presented as a target during the standard stimulus. The standard stimulus was followed by a test stimulus in which the target along with another amplitude-modulated carrier (the distractor) was presented. The listener determined if in the test stimulus, the target (which was presented along with the distractor) was higher or lower in modulation depth than when the target was presented alone as the standard stimulus. The target and distractor were either 1- or 4-kHz carriers modulated at one of ten depths of modulation during the test stimulus at modulation rates ranging from 4 to 64 Hz. SALT was used to estimate the relative weight listeners assigned to the target and distractor as a function of the difference between their modulation rates, both for target carrier frequencies above and for target carrier frequencies below the distractor carrier frequency. When the target and distractor were modulated at the same rate, the target and distractor weights were equal, indicating synthetic listening. When the target and distractor differed in modulation rate, the listener gave more weight to the target suggesting a form of analytic listening. The result demonstrate the applicability of SALT to studies of modulation and reinforce the claim that different spectral components modulated with the same modulation pattern are processed synthetically.

Interobserver variation in cell selection for DNA image cytometry.

AIMS: To describe a systematic investigation of interobserver differences in interpretation of nuclear morphology in preparations of small cell lung cancer (SCLC). METHODS: The screening/reviewing facility on the highly optimised microscope environment was used to individually tag 127 nuclei, chosen to reflect the spectrum of morphological appearances in nuclear preparations from three biopsy specimens of SCLC. Each nucleus was reviewed and labelled as control (lymphocyte), malignant or unsatisfactory by each of four observers. DNA histograms were plotted for each specimen using the nuclei identified as malignant by each participant. The histograms were compared in terms of identification of DNA stemlines and by calculation of a 5c exceeding rate (5cER). RESULTS: Interobserver variation in assessment of morphology was seen in 55.1% of nuclei. Disagreement occurred most frequently in the malignant/unsatisfactory category. Differences in morphological classification had little influence on histogram assessment by means of visual inspection but did show an effect on 5cER. CONCLUSIONS: There are significant interobserver differences in subjective assessment of nuclear morphology in cytometric preparations. This effect may seriously influence cytometric measurements.

Stimulus classification procedure for assessing the extent to which binaural processing is spectrally analytic or synthetic.

A two-dimensional stimulus classification paradigm was used to assess the extent to which listeners' processing of interaural delays at low frequencies is spectrally analytic or synthetic. Listeners were presented with a 753-Hz target with an interaural delay that varied from trial to trial, taking on one of ten values, five leading to the left ear and five leading to the right. A 553-Hz distractor component was simultaneously presented, with its interaural delay also presented at one of ten different values. During a block of 100 trials, each of the possible combinations of target and distractor delay was presented once, and only once, in a random order. Listeners were instructed to make left-right judgments based on the target delay. Each condition was repeated ten times, and the slopes of the best linear boundaries between left and right responses were used to derive the relative weights given to the target and distractor in judgments of laterality. Six of the nine listeners gave increasing weight to the target as the duration of the signals was increased from 25 or 50 to 400 ms. Three listeners showed little change with duration; one consistently gave equal weight to the target and distractor, two consistently gave greater weight to the target than to the distractor. The utility of classification paradigms in the study of multidimensional acoustic signals is discussed.

Relocation accuracy on HOME computerized microscopes.

A major practical advantage of the HOME (highly optimized microscope environment) computerized microscope is the facility for relocating cells or other microscopic objects. Features can be marked directly on the microscope image using a mouse-driven cursor, and an interactive finder can then be used to relocate the marked features. Tests on a prototype HOME microscope have shown that positions can be relocated with an accuracy of standard deviation (SD) < 7 microm. The marked features could also be relocated on a second HOME microscope, although with somewhat reduced accuracy (standard deviations of < 17 microm). The system provides a very user-friendly environment for tasks requiring relocation of microscopic objects.

A new approach to man-machine communication for computerized microscopy.

HOME is a new computerized microscope designed to assist pathologists and cytotechnicians in routine examinations. The HOME workstation is composed of a standard light microscope fitted with objective and stage encoders, and a built-in high resolution computer display which superimposes dialog, drawing, and messages onto the optical microscope image. The software runs under Windows 3.x and provides interactive facilities such as accurate localization and relocation of zones of interest, morphometric measurements, patient data access, and quality control processes.

Discrimination of interaural envelope delays: the effect of randomizing component starting phase.

The goal of this study was to examine the nature of envelope extraction in the discrimination of high-frequency waveforms on the basis of envelope delay. Threshold interaural envelope delays were measured for complexes consisting of three or five components for which the starting phases of all sinusoids were either sine phase or randomized between intervals of a two-alternative forced-choice (2-AFC) task. The center frequency was 4 kHz and the frequency separation was varied from 25 to 500 Hz. The results showed that thresholds were greater for the phase-randomized conditions than the sine-phase conditions. The phase effect tended to diminish with increasing frequency separation for three-component complexes but not for the five-component complexes. Sensitivity to envelope delay was better for five-component complexes than for three-component complexes at most frequency separations. In general, the results showed superior lateralization performance for conditions in which the envelope fluctuations were greater, a finding that is consistent with models of high-frequency binaural processing that include envelope extraction prior to binaural comparison.

The combination of interaural information across frequencies: the effects of number and spacing of components, onset asynchrony, and harmonicity.

Threshold interaural delays were measured for a single interaurally delayed low-frequency target component presented against a background of two, four, six, or eight diotic "distractor" components. In the first experiment, a 753-Hz target and the flanking distractor components were gated on and off simultaneously. In subsequent experiments, the distractors were gated on 25-200 ms prior to the target. In addition, the target and distractor components were given various harmonic configurations. In general, threshold interaural delays were higher in all conditions in which distractors were present relative to thresholds obtained for the target component in isolation. Subjects reported that the pitch of the target component was more salient when an onset asynchrony between the target and distractors was present, but the components were perceived as occupying a single intracranial position in spite of the various interaural delays across the frequency domain. These results suggest that binaural processing of stimuli consisting of a small number of low-frequency temporally overlapping components occurs in a spectrally synthetic manner in which interaural information is combined across the spectrum, even in situations in which the segregation of pitch information occurs.

Taxol-induced flexibility of microtubules and its reversal by MAP-2 and Tau.

When microtubules, ordinarily quite rigid structures, are treated in vitro with the anti-tumor drug taxol, they rapidly develop a wavy appearance and become strikingly flexible. A quantitative measure of their flexibility, the reciprocal statistical length, lambda, increases by an order of magnitude when taxol is bound. Subsequent addition of either of the microtubule-associated proteins MAP-2 or tau causes the flexibility to disappear. It can be restored again by removing the microtubule-associated protein. These results show that taxol changes microtubular structure substantially, probably by weakening the interactions between protofilaments, and that microtubule-associated proteins reverse these effects, possibly by bridging protofilaments. This structural change and the accompanying flexibility may contribute importantly to taxol's cytotoxic activity.