Dusty: an assistive mobile manipulator that retrieves dropped objects for people with motor impairments

People with physical disabilities have ranked object retrieval as a high-priority task for assistive robots. We have developed Dusty, a teleoperated mobile manipulator that fetches objects from the floor and delivers them to users at a comfortable height. In this paper, we first demonstrate the robot's high success rate (98.4%) when autonomously grasping 25 objects considered being important by people with amyotrophic lateral sclerosis (ALS). We tested the robot with each object in five different configurations on five types of flooring. We then present the results of an experiment in which 20 people with ALS operated Dusty. Participants teleoperated Dusty to move around an obstacle, pick up an object and deliver the object to themselves. They successfully completed this task in 59 out of 60 trials (3 trials each) with a mean completion time of 61.4 SD?=?20.5 seconds), and reported high overall satisfaction using Dusty (7-point Likert scale; 6.8 SD?=?0.6). Participants rated Dusty to be significantly easier to use than their own hands, asking family members, and using mechanical reachers (p?相似文献   

Comparison of Text versus Video for Teaching Laparoscopic Knot Tying in the Novice Surgeon: A Randomized,Controlled Trial

BackgroundVideo seems advantageous over traditional text as an educational tool in conceptually-based procedures such as laparoscopy. However, this has never been tested directly.ObjectiveThe purpose of this study was to compare the use of text versus video as an educational tool for laparoscopic training, through a randomized controlled trial.Study DesignProspective, randomized, controlled clinical trial (Canadian Task Force classification I).MethodsEighty (n = 80) medical students, who had no experience with tying a laparoscopic intracorporeal knot, were randomly taught to do so by either reading a text with accompanying pictures (n = 40) or watching a short video with audio of comparable content (n = 40). The participants were allowed to review the material for as long as they needed to achieve understanding of the procedure. They were then asked to tie a laparoscopic square knot in a box trainer, with a limit time of 15 minutes. Time to review the educational material(s), time to tie the knot(s), numbers of attempts at the task (n), and numbers of those who expressed understanding of the task (n) were recorded.ResultsThe number of participants who were able to complete the knot (n = 14 text v. n = 18 video, p = 0.49) and the average time needed for completion (479 s text v.494 s video, p = 0.38) were not statistically different in the two groups. However, time to review the material (407 s text v. 258 s video, p < 0.001), number of attempts at the task (15 text v. 5 video had n>2 attempts, p = 0.01), and number of those who expressed understanding when they could not complete the task (35% text v. 59% video, p = 0.047) were statistically different.ConclusionsThis is the first randomized trial evaluating video alone as an educational tool in laparoscopic training. It demonstrates that video is superior to text in achieving superior conceptual understanding, without improving operative times. Understanding through video instruction cannot make up for a lack of technical ability in novice surgeons.     

Prevention of hepatocarcinogenesis and increased susceptibility to acetaminophen-induced liver failure in transaldolase-deficient mice by N-acetylcysteine

Although oxidative stress has been implicated in acute acetaminophen-induced liver failure and in chronic liver cirrhosis and hepatocellular carcinoma (HCC), no common underlying metabolic pathway has been identified. Recent case reports suggest a link between the pentose phosphate pathway (PPP) enzyme transaldolase (TAL; encoded by TALDO1) and liver failure in children. Here, we show that Taldo1^–/– and Taldo1^+/– mice spontaneously developed HCC, and Taldo1^–/– mice had increased susceptibility to acetaminophen-induced liver failure. Oxidative stress in Taldo1^–/– livers was characterized by the accumulation of sedoheptulose 7-phosphate, failure to recycle ribose 5-phosphate for the oxidative PPP, depleted NADPH and glutathione levels, and increased production of lipid hydroperoxides. Furthermore, we found evidence of hepatic mitochondrial dysfunction, as indicated by loss of transmembrane potential, diminished mitochondrial mass, and reduced ATP/ADP ratio. Reduced β-catenin phosphorylation and enhanced c-Jun expression in Taldo1^–/– livers reflected adaptation to oxidative stress. Taldo1^–/– hepatocytes were resistant to CD95/Fas-mediated apoptosis in vitro and in vivo. Remarkably, lifelong administration of the potent antioxidant N-acetylcysteine (NAC) prevented acetaminophen-induced liver failure, restored Fas-dependent hepatocyte apoptosis, and blocked hepatocarcinogenesis in Taldo1^–/– mice. These data reveal a protective role for the TAL-mediated branch of the PPP against hepatocarcinogenesis and identify NAC as a promising treatment for liver disease in TAL deficiency.     

Cardiomyocyte PDGFR-β signaling is an essential component of the mouse cardiac response to load-induced stress

PDGFR is an important target for novel anticancer therapeutics because it is overexpressed in a wide variety of malignancies. Recently, however, several anticancer drugs that inhibit PDGFR signaling have been associated with clinical heart failure. Understanding this effect of PDGFR inhibitors has been difficult because the role of PDGFR signaling in the heart remains largely unexplored. As described herein, we have found that PDGFR-β expression and activation increase dramatically in the hearts of mice exposed to load-induced cardiac stress. In mice in which Pdgfrb was knocked out in the heart in development or in adulthood, exposure to load-induced stress resulted in cardiac dysfunction and heart failure. Mechanistically, we showed that cardiomyocyte PDGFR-β signaling plays a vital role in stress-induced cardiac angiogenesis. Specifically, we demonstrated that cardiomyocyte PDGFR-β was an essential upstream regulator of the stress-induced paracrine angiogenic capacity (the angiogenic potential) of cardiomyocytes. These results demonstrate that cardiomyocyte PDGFR-β is a regulator of the compensatory cardiac response to pressure overload–induced stress. Furthermore, our findings may provide insights into the mechanism of cardiotoxicity due to anticancer PDGFR inhibitors.     

Detection of Molecular Markers of Drug Resistance in 2009 Pandemic Influenza A (H1N1) Viruses by Pyrosequencing

The M2 blockers amantadine and rimantadine and the neuraminidase (NA) inhibitors (NAIs) oseltamivir and zanamivir are approved by the FDA for use for the control of influenza A virus infections. The 2009 pandemic influenza A (H1N1) viruses (H1N1pdm) are reassortants that acquired M and NA gene segments from a Eurasian adamantane-resistant swine influenza virus. NAI resistance in the H1N1pdm viruses has been rare, and its occurrence is mainly limited to oseltamivir-exposed patients. The pyrosequencing assay has been proven to be a useful tool in surveillance for drug resistance in seasonal influenza A viruses. We provide a protocol which allows the detection of adamantane resistance markers as well as the I43T change, which is unique to the H1N1pdm M2 protein. The protocol also allows the detection of changes at residues V116, I117, E119, Q136, K150, D151, D199, I223, H275, and N295 in the NA, known to alter NAI drug susceptibility. We report on the detection of the first cases of the oseltamivir resistance-conferring mutation H275Y and the I223V change in viruses from the United States using the approach described in this study. Moreover, the assay permits the quick identification of the major NA group (V106/N248, I106/D248, or I106/N248) to which a pandemic virus belongs. Pyrosequencing is well suited for the detection of drug resistance markers and signature mutations in the M and NA gene segments of the pandemic H1N1 influenza viruses.In the spring of 2009, an antigenically novel influenza A virus (H1N1) was detected in North America (7). The rapid widespread transmission of the virus resulted in the declaration of an influenza pandemic by the World Health Organization (WHO) (42). The 2009 pandemic influenza A (H1N1) virus (H1N1pdm) was determined to be a reassortant with a combination of gene segments that had not been previously described (12, 21). Phylogenetic analysis of the full genome sequences revealed that in the late 1990s, reassortment between seasonal influenza A virus (H3N2), classical swine influenza virus, and North American avian influenza viruses led to the appearance of triple-reassortant H3N2 and H1N2 swine influenza viruses that have since circulated in pigs in North America (40). The pandemic virus was a result of further reassortment between a triple-reassortant swine influenza virus and a Eurasian avian influenza virus-like swine influenza virus, resulting in the acquisition of two gene segments, coding for the M protein and neuraminidase (NA), from the Eurasian avian influenza virus-like swine influenza virus lineage. Recent genome sequence analysis performed with pandemic viruses collected in different regions found variants with characteristic amino acid changes, including 2 amino acid changes in the NA (21, 29). The reports identified three NA variants among the H1N1pdm viruses: one variant group has V106 and N248 (referred to as the A/California/04/2009 group); the second variant, named the A/Osaka/164/2009 group, is characterized by I106 and N248; and the third NA variant group contains I106 and D248, such as the A/New York/18/2009 strain.Currently circulating triple-reassortant swine influenza viruses in the United States do not contain any known markers of adamantane resistance (L26F, V27A, A30V, A30T, S31N, and G34E) (10, 25), whereas the Eurasian avian-like influenza viruses as well as the pandemic virus contain the adamantane resistance-conferring change S31N in the M2 protein. Currently, two classes of antiviral drugs are approved for use by the FDA for the control of influenza virus infections: adamantanes (M2 blockers) and neuraminidase inhibitors (NAIs). Resistance to adamantanes makes the NAIs oseltamivir and zanamivir the only pharmaceutical options available for use for the control of infections caused by the pandemic virus. Monitoring of resistance to NAIs is mainly based on the NA inhibition assay (23, 39, 41), which allows the detection of resistance conferred by known and novel mutations. However, the NA inhibition assay requires virus isolation and propagation, and the detection of resistance by the NA inhibition assay requires confirmation by sequencing of the NA gene segment to identify the markers of resistance and their presence in the original clinical material.Prior to the 2007-2008 influenza season, the frequency of resistance to NAIs had been very low (<0.5%) among field isolates (28, 35, 36). During the 2007-2008 influenza season, seasonal H1N1 viruses resistant to oseltamivir emerged and spread globally (3, 17, 31, 39), and by April of 2009, the majority of the H1N1 viruses were resistant to oseltamivir but sensitive to zanamivir. Of note, nearly all of the 2009 pandemic H1N1 viruses were sensitive to NAIs (8); only sporadic cases of oseltamivir-resistant viruses with the H275Y mutation in the NA gene segment were reported to the WHO, and they were mainly detected following antiviral drug treatment (5, 6, 42). The H275Y mutation is equivalent to the H274Y mutation in the N2 subtype amino acid numbering. Throughout the text, amino acids are described with the N1 numbering, and the corresponding N2 amino acid numbering is shown in parentheses, when it differs from the N1 numbering. Recent reports on the emergence of oseltamivir resistance highlight the need for close monitoring of the susceptibility of the pandemic H1N1 virus to the available drugs (5, 6, 42). Such information is needed to make informed decisions on measures aimed at managing pandemic virus infections.The molecular markers of NAI resistance are type and subtype specific and are also drug specific (1, 23). The H275Y (H274Y) change is the most commonly reported mutation conferring resistance to oseltamivir in the N1 subtype of NA. This change has been reported not only in seasonal H1N1 viruses but also in highly pathogenic H5N1 viruses (13, 22, 23, 31, 33). The H275Y (H274Y) mutation is also known to reduce susceptibility to the investigational NAI peramivir (23). The amino acid replacement N295S (N294S) in N1 has also been shown to reduce susceptibility to oseltamivir and zanamivir (33, 43). In addition, recent studies have demonstrated that mutations in other residues located in and around the NA active site can alter the susceptibilities of viruses to NAIs. For instance, changes at residues V116, I117, E119, Q136, D199 (D198), and I223 (I222) were associated with reduced susceptibility to NAIs in both seasonal and H5N1 viruses (26-28, 30, 32, 39). Moreover, crystal structure studies with the NAs of H1N1 and H5N1 viruses (9, 37) suggested that mutations at amino acids Q136, K150, and D151 (37) may affect susceptibility to oseltamivir and zanamivir, presumably by interfering with the binding of the drug to the NA. Changes at these residues were reported to reduce the susceptibilities to NAIs of viruses with the N1 enzyme (34; CDC, Atlanta, GA, unpublished data).It is important to develop the tools necessary for the rapid detection of NA markers known or suspected of affecting susceptibility to NAIs. Pyrosequencing has previously been shown to provide a rapid and high-throughput method for the detection of molecular markers of drug resistance in seasonal as well as highly pathogenic avian influenza viruses (4, 8, 15, 16, 19, 30, 31, 38).Here we report on the design and validation of pyrosequencing assays for the detection of signature markers in the M2 and NA gene segments of the pandemic H1N1 viruses.     

Assessment of Pandemic and Seasonal Influenza A (H1N1) Virus Susceptibility to Neuraminidase Inhibitors in Three Enzyme Activity Inhibition Assays

The neuraminidase inhibitors (NAIs) zanamivir and oseltamivir are currently the only antiviral drugs effective for the treatment and prophylaxis of 2009 pandemic influenza A (H1N1) virus infections. The proven potential of these viruses to acquire NAI resistance during treatment emphasizes the need to assess their NAI susceptibility. The 50% inhibitory concentrations (IC₅₀s) are known to vary depending on the neuraminidase inhibition (NI) test used; however, few side-by-side comparisons of different NI assays have been done. In the present study, a panel of 11 isolates representing 2009 seasonal and pandemic influenza H1N1 viruses, including oseltamivir-resistant H275Y variants, were tested in three functional NI assays: chemiluminescent (CL), fluorescent (FL), and colorimetric (CM). The sensitivities of the viruses to zanamivir, oseltamivir, and three investigational NAIs (peramivir, R-125489, and A-315675) were assessed. All isolates with the exception of H275Y variants were sensitive to all five NAIs by all three NI assays. The H275Y variants showed substantially elevated IC₅₀s against oseltamivir and peramivir. The three NI assays generally yielded consistent results; thus, the choice of NI assay does not appear to affect conclusions based on drug susceptibility surveillance. Each assay, however, offers certain advantages compared to the others: the CL assay required less virus volume and the FL assay provided the greatest difference in the IC₅₀s between the wild type and the variants, whereas the IC₅₀s obtained from the CM assay may be the most predictive of the drug concentrations needed to inhibit enzyme activity in humans. It would be desirable to develop an NI assay which combines the advantages of all three currently available assays but which lacks their shortcomings.For the treatment and chemoprophylaxis of infections caused by influenza A viruses, the U.S. Food and Drug Administration (FDA) has approved four drugs: amantadine and rimantadine as well as zanamivir and oseltamivir. These drugs belong to two classes, adamantanes (i.e., M2 ion-channel blockers) and neuraminidase (NA) inhibitors (NAIs), respectively. In recent years, the effectiveness of M2 blockers has been greatly compromised, which limits their usefulness in clinical practice. This is largely due to the rapid emergence and widespread circulation of adamantane-resistant influenza viruses (1, 5, 6, 7, 14, 17). More recently, the emergence and worldwide spread of seasonal H1N1 viruses resistant to oseltamivir, currently the most widely used drug against influenza infections, became a considerable public health concern (15, 21, 25, 32). Monitoring the NAI resistance of influenza viruses is an ongoing public health issue since the emergence in 2009 of pandemic viruses that are resistant to M2 blockers.Cell culture-based assays are typically not used for assessment of virus sensitivity to NAIs because of the unpredictable effect of hemagglutinin (HA) receptor binding (2, 34). Instead, drug susceptibility can be monitored by functional (biochemical) NA inhibition (NI) assays, and subsequent genotypic methods are generally required to identify the molecular marker(s) of resistance in the NA. The principle underlying the functional methods relies on the enzymatic nature of the NA, a viral surface glycoprotein and antigen. NA acts by cleaving the terminal neuraminic acid (also called sialic acid) from receptors recognized by influenza viral HA, thus facilitating the release of progeny virions from infected cells and preventing self-aggregation (29). Structurally, NAIs mimic the natural substrate, neuraminic acid, and produce tight interactions, with conserved residues of the NA active site competing with neuraminic acid for binding (11, 23). Preincubation of virus with NAIs leads to the inhibition of enzyme activity, which is detected after the addition of enzyme substrate. Most NI assays commonly used for virus surveillance utilize as substrates small synthetic conjugates that produce either a luminescent or a fluorescent signal upon cleavage by the NA enzyme. The chemiluminescent (CL) assay uses the 1,2-dioxetane derivative of neuraminic acid substrate in the influenza neuraminidase inhibitor resistance detection (NA-Star) kit (8), while the fluorescent (FL) assay employs 2′-O-(4-methylumbelliferyl)-N-acetylneuraminic acid substrate (MUNANA) (30). The results of the NI assays are expressed as the 50% inhibitory concentration (IC₅₀), which represents the NAI concentration that inhibits 50% of the enzyme activity of the virus. As the NA activity of clinical specimens is usually insufficient for determining the IC₅₀ due to a low viral content, NI assays, using either the substrate provided with the NA-Star kit or the MUNANA substrate, require virus propagation in cell cultures or embryonated chicken eggs. It is noteworthy that IC₅₀s are specific to the virus type/subtype and to the individual NAI tested (8, 19, 20, 24, 32, 37). The IC₅₀s obtained can be used for assessment of virus susceptibility to NAIs, including detection of resistant viruses, as well as for comparing the potencies of antiviral drugs belonging to the NAI class. Although both the CL and FL assays allow reliable detection of NAI resistance, the more recently developed CL assay was reported to be about 70 times more sensitive in detecting NA activity and has a greater linear range than the FL assay (8). The CL assay was also selected for use in the global drug susceptibility surveillance program by the Neuraminidase Inhibitor Susceptibility Network (NISN) (37, 39) and by other surveillance laboratories (28, 32). It should also be noted that IC₅₀s may vary even for the same virus when the NI assay is done using the NA-Star substrate (CL assay) and the MUNANA substrate (FL assay), according to reports on seasonal viruses (37). Whether one of the two assays, the CL or FL assay, more reliably predicts the level of resistance and the drug concentration required for the NA activity inhibition in vivo are key points of interest and remain to be elucidated.A third assay, the colorimetric (CM) assay, which utilizes fetuin as the substrate of the NA, is typically used to determine the titer of anti-NA antibodies because small substrates do not effectively compete with antibodies (3, 31). This assay is not widely used for antiviral susceptibility testing. Unlike the NA-Star and MUNANA synthetic substrates, fetuin is a large, natural, and soluble bovine glycoprotein that contains abundant neuraminic acids at the ends of its oligosaccharide moiety (which include the presence of two residues of α2,3-linked sialic acid and one residue of α2,6-linked sialic acid) (4, 33) and has been used as a substrate in NA-catalyzed reactions (3). Given that NAIs compete with the enzyme substrate for binding to the active site, the structure of the substrate can potentially influence the outcome of the competition and, as a result, the IC₅₀. In this respect, fetuin may represent a better natural substrate for the enzyme-neuraminic acid attached via an α2,3 or α2,6 linkage to oligosaccharide chains on the cell surface. Furthermore, since the cleavage of each neuraminic acid is chemically converted, the CM assay can be a quantifiable method from which the resulting IC₅₀s would correlate more closely to the NA activity of the virus tested. Despite these apparent advantages to the use of fetuin, the CM method relies on chemical reactions that are time-consuming, cumbersome, and impractical for high-throughput use. In addition, the assay requires concentrated virus stocks for testing. Thus, fetuin is still considered an undefined substrate that does not confer sufficient sensitivity or specificity for use in routine NAI susceptibility assays (34). The potential usefulness of a large substrate such as fetuin for assessment of the NAI susceptibilities of novel H1N1 viruses or novel inhibitors remains largely unexplored.Resistance to NAIs is not defined as clearly as that to adamantanes. In NI assays, a drug-resistant virus should have IC₅₀s consistently greater than the threshold value that is determined for each viral type/subtype and drug tested (27, 32, 37). Since the 2007-2008 influenza season, about a decade after the introduction of NAIs into clinical use, an NA framework mutation, H275Y (H274Y in N2 numbering), was consistently and most commonly detected in oseltamivir-resistant H1N1 viruses isolated worldwide (15, 21, 25, 32). Although the H275Y substitution represents the most-defined oseltamivir resistance marker of influenza viruses carrying the NA of the N1 subtype (35), novel NAI resistance-associated mutations—determined by elevated IC₅₀s in NI assays—continue to be revealed (21, 22, 32). Importantly, oseltamivir-resistant viruses from the ongoing H1N1 pandemic have been detected and reported around the world (9, 10, 26, 38). Seasonal and 2009 pandemic H1N1 viruses have the same phylogenetically distant NA gene ancestors (16), which necessitates the comprehensive assessment of the drug susceptibilities of the new pandemic viruses. Therefore, it is necessary to evaluate existing NI assays in order to better understand which assay may be the most sensitive for the detection of NAI resistance and/or the most predictive of virus susceptibility to NAIs in vivo.In the present study, we assessed the susceptibilities of a panel of seasonal and pandemic H1N1 influenza viruses, including virus variants bearing the established oseltamivir resistance mutation, H275Y in the NA, against five NAIs: two FDA-approved NAIs, zanamivir and oseltamivir, and three investigational NAIs, peramivir, R-125489 (the bioactive metabolite of the prodrug CS-8958 [laninamivir]), and A-315675 (a bioactive form of the prodrug A-322278). In order to better characterize and assess the consistency of IC₅₀s and levels of susceptibility, these viruses were tested in the widely used CL and FL assays, as well as with the CM method.