Elephant cognition in primate perspective

On many of the staple measures of comparative psychology, elephants show no obvious differences from other mammals, such as primates: discrimination learning, memory, spontaneous tool use, etc. However, a range of more naturalistic measures have recently suggested that elephant cognition may be rather different. Wild elephants sub-categorize humans into groups, independently making this classification on the basis of scent or colour. In number discrimination, elephants show no effects of absolute magnitude or relative size disparity in making number judgements. In the social realm, elephants show empathy into the problems faced by others, and give hints of special abilities in cooperation, vocal imitation and perhaps teaching. Field data suggest that the elephant’s vaunted reputation for memory may have a factual basis, in two ways. Elephants’ ability to remember large-scale space over long periods suggests good cognitive mapping skills. Elephants’ skill in keeping track of the current locations of many family members implies that working memory may be unusually developed, consistent with the laboratory finding that their quantity judgements do not show the usual magnitude effects.Publisher PDFPeer reviewe

Skull Flexure from Blast Waves: A Mechanism for Brain Injury with Implications for Helmet Design

Traumatic brain injury [TBI] has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well-researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that non-lethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design.Comment: version in press, Physical Review Letters; 17 pages, 5 figures (includes supplementary material

Measles Vaccination in HIV-Infected Children: Systematic Review and Meta-Analysis of Safety and Immunogenicity

Background. Measles control may be more challenging in regions with a high prevalence of HIV infection. HIV-infected children are likely to derive particular benefit from measles vaccines because of an increased risk of severe illness. However, HIV infection can impair vaccine effectiveness and may increase the risk of serious adverse events after receipt of live vaccines. We conducted a systematic review to assess the safety and immunogenicity of measles vaccine in HIV-infected children. Methods. The authors searched 8 databases through 12 February 2009 and reference lists. Study selection and data extraction were conducted in duplicate. Meta-analysis was conducted when appropriate. Results. Thirty-nine studies published from 1987 through 2008 were included. In 19 studies with information about measles vaccine safety, more than half reported no serious adverse events. Among HIV-infected children, 59% (95% confidence intervals [CI], 46-71%) were seropositive after receiving standard-titer measles vaccine at 6 months (1 study), comparable to the proportion of seropositive HIV-infected children vaccinated at 9 (8 studies) and 12 months (10 studies). Among HIV-exposed but uninfected and HIV-unexposed children, the proportion of seropositive children increased with increasing age at vaccination. Fewer HIV-infected children were protected after vaccination at 12 months than HIV-exposed but uninfected children (relative risk, 0.61; 95% CI, .50-.73). Conclusions. Measles vaccines appear to be safe in HIV-infected children, but the evidence is limited. When the burden of measles is high, measles vaccination at 6 months of age is likely to benefit children of HIV-infected women, regardless of the child's HIV infection statu

Modulation of the myogenic mechanism: concordant effects of NO synthesis inhibition and O 2 − dismutation on renal autoregulation in the time and frequency domains

Renal blood flow autoregulation was investigated in anesthetized C57Bl6 mice using time- and frequency-domain analyses. Autoregulation was reestablished by 15 s in two stages after a 25-mmHg step increase in renal perfusion pressure (RPP). The renal vascular resistance (RVR) response did not include a contribution from the macula densa tubuloglomerular feedback mechanism. Inhibition of nitric oxide (NO) synthase [NG-nitro-l-arginine methyl ester (l-NAME)] reduced the time for complete autoregulation to 2 s and induced 0.25-Hz oscillations in RVR. Quenching of superoxide (SOD mimetic tempol) during l-NAME normalized the speed and strength of stage 1 of the RVR increase and abolished oscillations. The slope of stage 2 was unaffected by l-NAME or tempol. These effects of l-NAME and tempol were evaluated in the frequency domain during random fluctuations in RPP. NO synthase inhibition amplified the resonance peak in admittance gain at 0.25 Hz and markedly increased the gain slope at the upper myogenic frequency range (0.06–0.25 Hz, identified as stage 1), with reversal by tempol. The slope of admittance gain in the lower half of the myogenic frequency range (equated with stage 2) was not affected by l-NAME or tempol. Our data show that the myogenic mechanism alone can achieve complete renal blood flow autoregulation in the mouse kidney following a step increase in RPP. They suggest also that the principal inhibitory action of NO is quenching of superoxide, which otherwise potentiates dynamic components of the myogenic constriction in vivo. This primarily involves the first stage of a two-stage myogenic response

The burden of malaria in post-emergency refugee sites: A retrospective study

<p>Abstract</p> <p>Background</p> <p>Almost two-thirds of refugees, internally displaced persons, returnees and other persons affected by humanitarian emergencies live in malaria endemic regions. Malaria remains a significant threat to the health of these populations.</p> <p>Methods</p> <p>Data on malaria incidence and mortality were analyzed from January 2006 to December 2009 from the United Nations High Commissioner for Refugees Health Information System database collected at sites in Burundi, Chad, Cameroon, Ethiopia, Kenya, Sudan, Tanzania, Thailand, and Uganda. Data from three countries during 2006 and 2007, and all nine countries from 2008 to 2009, were used to describe trends in malaria incidence and mortality. Monthly counts of malaria morbidity and mortality were aggregated into an annual country rate averaged over the study period.</p> <p>Results</p> <p>An average of 1.18 million refugees resided in 60 refugee sites within nine countries with at least 50 cases of malaria per 1000 refugees during the study period 2008-2009. The highest incidence of malaria was in refugee sites in Tanzania, where the annual incidence of malaria was 399 confirmed cases per 1,000 refugees and 728 confirmed cases per 1,000 refugee children younger than five years. Malaria incidence in children younger than five years of age, based on the sum of confirmed and suspected cases, declined substantially at sites in two countries between 2006 and 2009, but a slight increase was reported at sites within four of seven countries between 2008 and 2009. Annual malaria mortality rates were highest in sites in Sudan (0.9 deaths per 1,000 refugees), Uganda and Tanzania (0.7 deaths per 1000 refugees each). Malaria was the cause of 16% of deaths in refugee children younger than five years of age in all study sites.</p> <p>Conclusions</p> <p>These findings represent one of the most extensive reports on malaria among refugees in post-emergency sites. Despite declines in malaria incidence among refugees in several countries, malaria remains a significant cause of mortality among children younger than five years of age. Further progress in malaria control, both within and outside of post-emergency sites, is necessary to further reduce malaria incidence and mortality among refugees and achieve global goals in malaria control and elimination.</p

Do children infected with HIV receiving HAART need to be revaccinated?

No offi cial recommendations have been made on whether children infected with HIV on highly active antiretroviral therapy (HAART) should be revaccinated. We reviewed published work to establish whether these children have protective immunity to vaccine-preventable diseases and to assess short-term and long-term immune responses to vaccination of children given HAART. In general, children on HAART had low levels of immunity to vaccines given before treatment. Most children on HAART, however, responded to revaccination, although immune reconstitution was not suffi cient to ensure long-term immunity for some children. These results suggest that children on HAART would benefi t from revaccination, but levels of protective immunity might need to be monitored and some children might need additional vaccine doses to maintain protective immunity. Vaccination policies and strategies for children infected with HIV on HAART should be developed in regions of high HIV prevalence to ensure adequate individual and population immunity

Flexibility and intrinsic disorder are conserved features of hepatitis C virus E2 glycoprotein

The glycoproteins of hepatitis C virus, E1E2, are unlike any other viral fusion machinery yet described, and are the current focus of immunogen design in HCV vaccine development; thus, making E1E2 both scientifically and medically important. We used pre-existing, but fragmentary, structures to model a complete ectodomain of the major glycoprotein E2 from three strains of HCV. We then performed molecular dynamic simulations to explore the conformational landscape of E2, revealing a number of important features. Despite high sequence divergence, and subtle differences in the models, E2 from different strains behave similarly, possessing a stable core flanked by highly flexible regions, some of which perform essential functions such as receptor binding. Comparison with sequence data suggest that this consistent behaviour is conferred by a network of conserved residues that act as hinge and anchor points throughout E2. The variable regions (HVR-1, HVR-2 and VR-3) exhibit particularly high flexibility, and bioinformatic analysis suggests that HVR-1 is a putative intrinsically disordered protein region. Dynamic cross-correlation analyses demonstrate intramolecular communication and suggest that specific regions, such as HVR-1, can exert influence throughout E2. To support our computational approach we performed small-angle X-ray scattering with purified E2 ectodomain; this data was consistent with our MD experiments, suggesting a compact globular core with peripheral flexible regions. This work captures the dynamic behaviour of E2 and has direct relevance to the interaction of HCV with cell-surface receptors and neutralising antibodies

Suppression of human immunodeficiency virus replication during acute measles.

To determine the effect of measles virus coinfection on plasma human immunodeficiency virus (HIV) RNA levels, a prospective study of hospitalized children with measles was conducted between January 1998 and October 2000 in Lusaka, Zambia. Plasma HIV RNA levels were measured during acute measles and 1 month after hospital discharge. The median plasma HIV RNA level in 33 children with measles who were followed longitudinally was 5339 copies/mL at study entry, 60,121 copies/mL at hospital discharge, and 387,148 copies/mL at 1-month follow-up. The median plasma HIV RNA level in children without acute illness was 228,454 copies/mL. Plasma levels of immune activation markers were elevated during the period of reduced plasma HIV RNA. Plasma levels of several potential HIV suppressive factors also were elevated during acute measles. HIV replication is transiently suppressed during acute measles at a time of intense immune activation

Identification of Variegated Coloring in Skin Tumors: Neural Network vs. Rule-Based Induction Methods

The use of neural networks for automatic identification of variegated coloring, which is believed to be one of the most predictive features for malignant melanoma, is described. The Nestor development system (NDS) was chosen for neural network implementation. At the heart of NDS is a three-layer neural network called a restricted Coulomb energy (RCE) network. The learning scheme and the database for detection of variegated coloring are discussed. Results are reporte