View-Invariant Visuomotor Processing in Computational Mirror Neuron System for Humanoid

Mirror neurons are visuo-motor neurons found in primates and thought to be significant for imitation learning. The proposition that mirror neurons result from associative learning while the neonate observes his own actions has received noteworthy empirical support. Self-exploration is regarded as a procedure by which infants become perceptually observant to their own body and engage in a perceptual communication with themselves. We assume that crude sense of self is the prerequisite for social interaction. However, the contribution of mirror neurons in encoding the perspective from which the motor acts of others are seen have not been addressed in relation to humanoid robots. In this paper we present a computational model for development of mirror neuron system for humanoid based on the hypothesis that infants acquire MNS by sensorimotor associative learning through self-exploration capable of sustaining early imitation skills. The purpose of our proposed model is to take into account the view-dependency of neurons as a probable outcome of the associative connectivity between motor and visual information. In our experiment, a humanoid robot stands in front of a mirror (represented through self-image using camera) in order to obtain the associative relationship between his own motor generated actions and his own visual body-image. In the learning process the network first forms mapping from each motor representation onto visual representation from the self-exploratory perspective. Afterwards, the representation of the motor commands is learned to be associated with all possible visual perspectives. The complete architecture was evaluated by simulation experiments performed on DARwIn-OP humanoid robot.     

A Patient-Centered Understanding of the Referral System in Ethiopian Primary Health Care Units

Background

Primary healthcare systems in sub-Saharan Africa have undergone substantial development in an effort to expand access to appropriate facilities through a well-functioning referral system. The objective of this study was to evaluate the current patterns of seeking prior care before arriving at a health center or a hospital as a key aspect of the referral system of the primary health care unit (PHCU) in three regions in Ethiopia. We examined what percentage of patients had either sought prior care or had been referred to the present facility and identified demographic and clinical factors associated with having sought prior care or having been referred.

Methods and Findings

We conducted a cross-sectional study using face-to-face interviews in the local language with 796 people (99% response rate) seeking outpatient care in three primary health care units serving approximately 100,000 people each and reflecting regional and ethnic diversity; 53% (N = 418) of the sample was seeking care at hospital outpatient departments, and 47% of the sample was seeking care at health centers (N = 378). We used unadjusted and adjusted logistic regression to identify factors associated with having been referred or sought prior care. Our findings indicated that only 10% of all patients interviewed had been referred to their current place of care. Among those in the hospital population, 14% had been referred; among those in the health center population, only 6% had been referred. Of those who had been referred to the hospital, most (74%) had been referred by a health center. Among those who were referred to the health center, the plurality portion (32%) came from a nearby hospital (most commonly for continued HIV treatment or early childhood vaccinations); only 18% had come from a health post. Among patients who had not been formally referred, an additional 25% in the hospital sample and 10% in the health center sample had accessed some prior source of care for their present health concern. In the adjusted analysis, living a longer distance from the source of care and needing more specialized care were correlated with having sought prior care in the hospital sample. We found no factors significantly associated with having sought prior care in the health center sample.

Conclusions

The referral system among health facilities in Ethiopia is used by a minority of patients, suggesting that intended connections between health posts, health centers, and hospitals may need strengthening to increase the efficiency of primary care nationally.     

Molecular analysis of the TMPRSS3 gene in Moroccan families with non-syndromic hearing loss

Autosomal recessive non-syndromic hearing impairment (ARNSHI) is the most common type of inherited hearing impairment, accounting for approximately 80% of inherited prelingual hearing impairment. Hearing loss is noted to be both phenotypically and genetically heterogeneous. Mutations in the TMPRSS3 gene, which encodes a transmembrane serine protease, are known to cause autosomal recessive non-syndromic hearing impairment DFNB8/10. In order to elucidate if the TMPRSS3 gene is responsible for ARNSHI in 80 Moroccan families with non-syndromic hearing impairment, the gene was sequenced using DNA samples from these families. Nineteen TMPRSS3 variants were found, nine are located in the exons among which six are missense and three are synonymous. The 10 remaining variations are located in non-coding regions. Missense variants analysis show that they do not have a significant pathogenic effect on protein while pathogenicity of some variant remains under discussion. Thus we show that the TMPRSS3 gene is not a major contributor to non-syndromic deafness in the Moroccan population.     

Poly(styrenesulfonate)/poly(allylamine) multilayers: a route to favor endothelial cell growth on expanded poly(tetrafluoroethylene) vascular grafts

Small-diameter synthetic vascular grafts of expanded poly(tetrafluoroethylene) (ePTFE) polymer concern one of the most common alternatives for the replacement of diseased vessels. However, high failure rates arise especially due to the lack of endothelial cells (ECs). EC seeding was developed to build a monolayer on the luminal surface. Because ECs show little or no adhesion on synthetic prostheses, it is necessary to promote their retention. On ePTFE surfaces we successfully deposited polyelectrolyte multilayer films (PMFs) consisting of poly(ethylenimine) (PEI), poly(sodium 4-styrenesulfonate) (PSS), and poly(allylamine hydrochloride) (PAH) to obtain PEI-(PSS-PAH)3 films. EC adhesion and spreading on modified ePTFE were assessed by scanning electron and confocal microscopies. Cell viability was evaluated by Alamar Blue assay. After 7 days of culture, the ePTFE modified with PMF exhibited improvements of EC viability as compared to that of the controls (nonmodified ePTFE) or even ePTFE coated by a PAH monolayer (p < 0.05). Moreover, the spreading of ECs was largely enhanced compared to that of the same controls, resulting in a healthy confluent cell monolayer formation. Positive staining for the von Willebrand factor confirmed the EC phenotype. Promoting EC attachment and function on ePTFE modified with PMFs could become in the future a promising treatment for synthetic small-diameter vascular grafts.     

GABAergic neurosteroids: the "endogenous benzodiazepines" of acute liver failure

Acute liver failure (ALF) or fulminant hepatic failure represents a serious life-threatening condition. ALF is characterized by a significant liver injury that leads to a rapid onset of hepatic encephalopathy (HE). In ALF, patients manifest rapid deterioration in consciousness leading to hepatic coma together with an onset of brain edema which induces high intracranial pressure that frequently leads to herniation and death. It is well accepted that hyperammonemia is a cardinal, but not the sole, mediator in the pathophysiology of ALF. There is increasing evidence that neurosteroids, including the parent neurosteroid pregnenolone, and the progesterone metabolites tetrahydroprogesterone (allopregnanolone) and tetrahydrodeoxycorticosterone (THDOC) accumulate in brain in experimental models of ALF. Neurosteroids in ALF represent good candidates to explain the phenomenon of "increased GABAergic tone" in chronic and ALF, and the beneficial effects of benzodiazepine drugs. The mechanisms that trigger brain neurosteroid changes in ALF are not yet well known, but could involve partially de novo neurosteroidogenesis following activation of the translocator protein (TSPO). The factors that contribute to TSPO changes in ALF may include ammonia and cytokines. It is possible that increases in brain levels of neurosteroids in ALF may result in auto-regulatory mechanisms where hypothermia may play a significant role. Possible mechanisms that may involve neurosteroids in the pathophysiology of HE, and more speculatively in brain edema, and inflammatory processes in ALF are suggested.     

Hepatitis C virus infection among First Nation and non-First Nation people in Manitoba, Canada: a public health laboratory study

Demographic information and laboratory test results on 136 169 clinical serum specimens submitted to the public health laboratory in Manitoba, Canada, for hepatitis C virus (HCV) testing between January 1995 and December 2003 were analyzed. The difference in the clearance rates of HCV infection, without therapeutic intervention, and the HCV genotypes infecting First Nation and non-First Nation people were studied. The rates of co-infection of HCV-positive individuals with other hepatitis viruses were also compared between the two study groups. The results of the analyses of the data indicated that there was a 4.4-fold increase in the number of specimens tested and a 4.9-fold decrease in HCV antibody (anti-HCV) positive cases during the study period. The proportion of specimens submitted for testing from First Nation individuals was lower than their proportion in the Manitoba population. Our study also indicated that there was a significantly higher proportion of First Nation patients who had self-limiting infection (patients cleared the infection and became HCV RNA negative without anti-HCV treatment) in comparison to non-First Nation patients. The proportion of First Nation females who had self-limiting infection was significantly higher than non-First Nation females. HCV genotype 1 infection represented more than 60% of HCV infection in Manitoba. The rate of individuals positive for the hepatitis A virus antibody in the HCV-positive population was higher among First Nation than non-First Nation individuals. On the other hand, there were more HCV-infected First Nation patients than non-First Nation patients who were not immune to the hepatitis B virus. The data indicate that fewer First Nation patients seek anti-HCV therapy in comparison to non-First Nation. In conclusion, the differences in the rates of HCV self-limiting infection between First Nation and non-First Nation individuals in Manitoba may reflect the genetic differences between the two cohorts, which may consequently affect the immune response to the HCV infection.     

Estimated cumulative incidence of pandemic (H1N1) influenza among pregnant women during the first wave of the 2009 pandemic

Background

Hospitalization and lab confirmed cases of H1N1 have been reported during the first wave of the 2009 pandemic but these are not accurate measures of influenza incidence in the population. We estimated the cumulative incidence of pandemic (H1N1) influenza among pregnant women in the province of Manitoba during the first wave of the 2009 pandemic.

Methods

Two panels of stored frozen serum specimens collected for routine prenatal screening were randomly selected for testing before (March 2009, n = 252) and after (August 2009, n = 296) the first wave of the pandemic. A standard hemagglutination inhibition assay was used to detect the presence of IgG antibodies against the pandemic (H1N1) 2009 virus. The cumulative incidence of pandemic (H1N1) influenza was calculated as the difference between the point prevalence rates in the first and second panels.

Results

Of the specimens collected in March, 7.1% were positive for the IgG antibodies (serum antibody titre ≥ 1:40). The corresponding prevalence was 15.7% among the specimens collected in August. The difference indicated a cumulative incidence of 8.6% (95% confidence interval [CI] 3.2%–13.7%). The rate differed geographically, the highest being in the northern regions (20.8%, 95% CI 7.9%–31.8%), as compared with 4.0% (95% CI 0.0%–11.9%) in Winnipeg and 8.9% (95% CI 0.0%–18.8%) in the rest of the province.

Interpretation

We estimated that the cumulative incidence of pandemic (H1N1) influenza among pregnant women in Manitoba during the first wave of the 2009 pandemic was 8.6%. It was 20.8% in the northern regions of the province.During the first wave of the pandemic (H1N1) 2009, the province of Manitoba was more severely affected than almost any other Canadian province.¹ Pregnant women in particular had higher rates of laboratory-confirmed infection and of severe illness.² However, the number of laboratory-confirmed cases is not an accurate measure of the incidence of influenza in the population. The number and geographic distribution of confirmed cases are influenced by differences in access to medical care, physicians’ practices and other factors.³We estimated the cumulative incidence of pandemic (H1N1) influenza among pregnant women in the province of Manitoba during the first wave of the 2009 pandemic. We did this by measuring the point seroprevalence in random samples of pregnant women presenting for routine prenatal screening before and after the first wave.     

Strobilanthes crispus attenuates renal carcinogen, iron nitrilotriacetate (Fe-NTA)-mediated oxidative damage of lipids and DNA

This study was aimed to evaluate the effect of Strobilanthes crispus extract for possible protection against lipid peroxidation and DNA damage induced by iron nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H₂O₂). Fe-NTA is a potent nephrotoxic agent and induces acute and subacute renal proximal tubular necrosis by catalyzing the decomposition of H₂O₂-derived production of hydroxyl radicals, which are known to cause lipid peroxidation and DNA damage. Incubation of postmitochondrial supernatant and/or calf thymus DNA with H₂O₂ (40 mM) in the presence of Fe-NTA (0.1 mM) induces lipid peroxidation and DNA damage to about 2.3-fold and 2.9-fold, respectively, as compared to control (P < 0.05). In lipid peroxidation protection studies, S. crispus treatment showed a dose-dependent inhibition (45–53% inhibition, P < 0.05) of Fe-NTA and H₂O₂ induced lipid peroxidation. Similarly, in DNA damage protection studies, S. crispus treatment also showed a dose-dependent inhibition (18–30% inhibition, P < 0.05) of DNA damage. In addition, the protection was closely related to the content of phenolic compounds as evident by S. crispus extract showing the value of 124.48 mg/g total phenolics expressed as gallic acid equivalent (GAE, mg/g of extract). From these studies, it is concluded that S. crispus inhibits peroxidation of membrane lipids and DNA damage induced by Fe-NTA and H₂O₂ and possesses the potential to be used to treat or prevent degenerative diseases where oxidative stress is implicated.