Recursos de Sanidad, Biomedicina y Salud

Noticias Externas del Tuesday 06 de March de 2012

PLoS Medicine

by Margaret Urban, Emily Banks, Sam Egger, Karen Canfell, Dianne O'Connell, Valerie Beral, Freddy Sitas


Oral contraceptives are known to influence the risk of cancers of the female reproductive system. Evidence regarding the relationship between injectable contraceptives and these cancers is limited, especially in black South Africans, among whom injectable contraceptives are used more commonly than oral contraceptives.

Methods and Findings

We analysed data from a South African hospital-based case–control study of black females aged 18–79 y, comparing self-reported contraceptive use in patients with breast (n = 1,664), cervical (n = 2,182), ovarian (n = 182), and endometrial (n = 182) cancer, with self-reported contraceptive use in 1,492 control patients diagnosed with cancers with no known relationship to hormonal contraceptive use. We adjusted for potential confounding factors, including age, calendar year of diagnosis, education, smoking, alcohol, parity/age at first birth, and number of sexual partners. Among controls, 26% had used injectable and 20% had used oral contraceptives. For current and more recent users versus never users of oral or injectable contraceptives, the odds ratios (ORs) for breast cancer were significantly increased in users of oral and/or injectable contraceptives (OR 1.66, 95% CI 1.28–2.16, p


by Hadley K. Herbert, Anne CC Lee, Aruna Chandran, Igor Rudan, Abdullah H. Baqui


Despite recent achievements to reduce child mortality, neonatal deaths continue to remain high, accounting for 41% of all deaths in children under five years of age worldwide, of which over 90% occur in low- and middle-income countries (LMICs). Infections are a leading cause of death and limitations in care seeking for ill neonates contribute to high mortality rates. As estimates for care-seeking behaviors in LMICs have not been studied, this review describes care seeking for neonatal illnesses in LMICs, with particular attention to type of care sought.

Methods and Findings

We conducted a systematic literature review of studies that reported the proportion of caregivers that sought care for ill or suspected ill neonates in LMICs. The initial search yielded 784 studies, of which 22 studies described relevant data from community household surveys, facility-based surveys, and intervention trials. The majority of studies were from South Asia (n = 17/22), set in rural areas (n = 17/22), and published within the last 4 years (n = 18/22). Of the 9,098 neonates who were ill or suspected to be ill, 4,320 caregivers sought some type of care, including care from a health facility (n = 370) or provider (n = 1,813). Care seeking ranged between 10% and 100% among caregivers with a median of 59%. Care seeking from a health care provider yielded a similar range and median, while care seeking at a health care facility ranged between 1% and 100%, with a median of 20%. Care-seeking estimates were limited by the few studies conducted in urban settings and regions other than South Asia. There was a lack of consistency regarding illness, care-seeking, and care provider definitions.


There is a paucity of data regarding newborn care-seeking behaviors; in South Asia, care seeking is low for newborn illness, especially in terms of care sought from health care facilities and medically trained providers. There is a need for representative data to describe care-seeking patterns in different geographic regions and better understand mechanisms to enhance care seeking during this vulnerable time period.

Please see later in the article for the Editors' Summary


by Xavier Bosch-Capblanch, John N. Lavis, Simon Lewin, Rifat Atun, John-Arne Røttingen, Daniel Dröschel, Lise Beck, Edgardo Abalos, Fadi El-Jardali, Lucy Gilson, Sandy Oliver, Kaspar Wyss, Peter Tugwell, Regina Kulier, Tikki Pang, Andy Haines


by Daniel F. Mackay, Scott M. Nelson, Sally J. Haw, Jill P. Pell


Both active smoking and environmental tobacco smoke exposure are associated with pregnancy complications. In March 2006, Scotland implemented legislation prohibiting smoking in all wholly or partially enclosed public spaces. The aim of this study was to determine the impact of this legislation on preterm delivery and small for gestational age.

Methods and Findings

We conducted logistic regression analyses using national administrative pregnancy data covering the whole of Scotland. Of the two breakpoints tested, 1 January 2006 produced a better fit than the date when the legislation came into force (26 March 2006), suggesting an anticipatory effect. Among the 716,941 eligible women who conceived between August 1995 and February 2009 and subsequently delivered a live-born, singleton infant between 24 and 44 wk gestation, the prevalence of current smoking fell from 25.4% before legislation to 18.8% after legislation (p

PLoS Neglected Tropical Diseases

by Wolfgang Beyer, Steve Bellan, Gisela Eberle, Holly H. Ganz, Wayne M. Getz, Renate Haumacher, Karen A. Hilss, Werner Kilian, Judith Lazak, Wendy C. Turner, Peter C. B. Turnbull

The recent development of genetic markers for Bacillus anthracis has made it possible to monitor the spread and distribution of this pathogen during and between anthrax outbreaks. In Namibia, anthrax outbreaks occur annually in the Etosha National Park (ENP) and on private game and livestock farms. We genotyped 384 B. anthracis isolates collected between 1983–2010 to identify the possible epidemiological correlations of anthrax outbreaks within and outside the ENP and to analyze genetic relationships between isolates from domestic and wild animals. The isolates came from 20 animal species and from the environment and were genotyped using a 31-marker multi-locus-VNTR-analysis (MLVA) and, in part, by twelve single nucleotide polymorphism (SNP) markers and four single nucleotide repeat (SNR) markers. A total of 37 genotypes (GT) were identified by MLVA, belonging to four SNP-groups. All GTs belonged to the A-branch in the cluster- and SNP-analyses. Thirteen GTs were found only outside the ENP, 18 only within the ENP and 6 both inside and outside. Genetic distances between isolates increased with increasing time between isolations. However, genetic distance between isolates at the beginning and end of the study period was relatively small, indicating that while the majority of GTs were only found sporadically, three genetically close GTs, accounting for more than four fifths of all the ENP isolates, appeared dominant throughout the study period. Genetic distances among isolates were significantly greater for isolates from different host species, but this effect was small, suggesting that while species-specific ecological factors may affect exposure processes, transmission cycles in different host species are still highly interrelated. The MLVA data were further used to establish a model of the probable evolution of GTs within the endemic region of the ENP. SNR-analysis was helpful in correlating an isolate with its source but did not elucidate epidemiological relationships.

by Jose Luis Ramirez, Jayme Souza-Neto, Rolando Torres Cosme, Jose Rovira, Alma Ortiz, Juan M. Pascale, George Dimopoulos

Dengue virus is one of the most important arboviral pathogens and the causative agent of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. It is transmitted between humans by the mosquitoes Aedes aegypti and Aedes albopictus, and at least 2.5 billion people are at daily risk of infection. During their lifecycle, mosquitoes are exposed to a variety of microbes, some of which are needed for their successful development into adulthood. However, recent studies have suggested that the adult mosquito's midgut microflora is critical in influencing the transmission of human pathogens. In this study we assessed the reciprocal interactions between the mosquito's midgut microbiota and dengue virus infection that are, to a large extent, mediated by the mosquito's innate immune system. We observed a marked decrease in susceptibility to dengue virus infection when mosquitoes harbored certain field-derived bacterial isolates in their midgut. Transcript abundance analysis of selected antimicrobial peptide genes suggested that the mosquito's microbiota elicits a basal immune activity that appears to act against dengue virus infection. Conversely, the elicitation of the mosquito immune response by dengue virus infection itself influences the microbial load of the mosquito midgut. In sum, we show that the mosquito's microbiota influences dengue virus infection of the mosquito, which in turn activates its antibacterial responses.

by Romano Ngui, Yvonne Ai Lian Lim, Liam Chong Kin, Chow Sek Chuen, Shukri Jaffar


Given that micronutrient deficiency, neglected intestinal parasitic infections (IPIs) and poor socioeconomic status are closely linked, we conducted a cross-sectional study to assess the relationship between IPIs and nutritional status of children living in remote and rural areas in West Malaysia.


A total of 550 children participated, comprising 520 (94.5%) school children aged 7 to 12 years old, 30 (5.5%) young children aged 1 to 6 years old, 254 (46.2%) boys and 296 (53.8%) girls. Of the 550 children, 26.2% were anaemic, 54.9% iron deficient and 16.9% had iron deficiency anaemia (IDA). The overall prevalence of helminths was 76.5% comprising Trichuris trichiura (71.5%), Ascaris lumbricoides (41.6%) and hookworm infection (13.5%). It was observed that iron deficiency was significantly higher in girls (p = 0.032) compared to boys. Univariate analysis demonstrated that low level of mother's education (OR = 2.52; 95% CI = 1.38–4.60; p = 0.002), non working parents (OR = 2.18; 95% CI = 2.06–2.31; p = 0.013), low household income (OR = 2.02; 95% CI = 1.14–3.59; p = 0.015), T. trichiura (OR = 2.15; 95% CI = 1.21–3.81; p = 0.008) and A. lumbricoides infections (OR = 1.63; 95% CI = 1.04–2.55; p = 0.032) were significantly associated with the high prevalence of IDA. Multivariate analysis confirmed that low level of mother's education (OR = 1.48; 95 CI% = 1.33–2.58; p


by Hebe Gouda, John Powles, Jan Barendregt, Paul Emerson, Jeremiah Ngondi


Trachoma is a disease that can lead to visual impairment and ultimately blindness. Previous estimates of health losses from trachoma using the Global Burden of Disease methodology have not, however, included the stage prior to visual impairment. We estimated the burden of all stages of trachoma in South Sudan and assessed the uncertainty associated with the severity and duration of stages of trachoma prior to full blindness.


The prevalence of trachoma with normal vision, low vision and blindness in the Republic of South Sudan has been estimated previously. These estimates were used to model the incidence and duration of the different stages employing DISMOD II. Different assumptions about disability weights and duration were used to estimate the Years Lived with Disability (YLD).


We have estimated the total burden of trachoma in South Sudan to be between 136,562 and 163,695 YLD and trichiasis with normal vision contributes between 5% and 21% of the total depending on the disability weight applied. Women experience more of this burden than men. The sensitivity of the results to different assumptions about the disability weights is partly dependent upon the assumed duration of the different disease states.


A better understanding of the natural history of trachoma is critical for a more accurate burden estimate.


by Femkje A. M. Jonker, Job C. J. Calis, Kamija Phiri, Eric A. T. Brienen, Harriet Khoffi, Bernard J. Brabin, Jaco J. Verweij, Michael Boele van Hensbroek, Lisette van Lieshout


Hookworm infections are an important cause of (severe) anemia and iron deficiency in children in the tropics. Type of hookworm species (Ancylostoma duodenale or Necator americanus) and infection load are considered associated with disease burden, although these parameters are rarely assessed due to limitations of currently used diagnostic methods. Using multiplex real-time PCR, we evaluated hookworm species-specific prevalence, infection load and their contribution towards severe anemia and iron deficiency in pre-school children in Malawi.

Methodology and Findings

A. duodenale and N. americanus DNA loads were determined in 830 fecal samples of pre-school children participating in a case control study investigating severe anemia. Using multiplex real-time PCR, hookworm infections were found in 34.1% of the severely anemic cases and in 27.0% of the non-severely anemic controls (p


by Sebastian Ziewer, Marc P. Hübner, Bettina Dubben, Wolfgang H. Hoffmann, Odile Bain, Coralie Martin, Achim Hoerauf, Sabine Specht


Lymphatic filariasis and onchocerciasis are two chronic diseases mediated by parasitic filarial worms causing long term disability and massive socioeconomic problems. Filariae are transmitted by blood-feeding mosquitoes that take up the first stage larvae from an infected host and deliver it after maturation into infective stage to a new host. After closure of vector control programs, disease control relies mainly on mass drug administration with drugs that are primarily effective against first stage larvae and require many years of annual/biannual administration. Therefore, there is an urgent need for alternative treatment ways, i.e. other effective drugs or vaccines.

Methodology/Principal Findings

Using the Litomosoides sigmodontis murine model of filariasis we demonstrate that immunization with microfilariae together with the adjuvant alum prevents mice from developing high microfilaraemia after challenge infection. Immunization achieved 70% to 100% protection in the peripheral blood and in the pleural space and furthermore strongly reduced the microfilarial load in mice that remained microfilaraemic. Protection was associated with the impairment of intrauterine filarial embryogenesis and with local and systemic microfilarial-specific host IgG, as well as IFN-γ secretion by host cells from the site of infection. Furthermore immunization significantly reduced adult worm burden.


Our results present a tool to understand the immunological basis of vaccine induced protection in order to develop a microfilariae-based vaccine that reduces adult worm burden and prevents microfilaraemia, a powerful weapon to stop transmission of filariasis.


by Ignacio Bolivar, Katrine Whiteson, Benoît Stadelmann, Denise Baratti-Mayer, Yann Gizard, Andrea Mombelli, Didier Pittet, Jacques Schrenzel, The Geneva Study Group on Noma (GESNOMA)


Noma is a gangrenous disease that leads to severe disfigurement of the face with high morbidity and mortality, but its etiology remains unknown. Young children in developing countries are almost exclusively affected. The purpose of the study was to record and compare bacterial diversity in oral samples from children with or without acute noma or acute necrotizing gingivitis from a defined geographical region in Niger by culture-independent molecular methods.

Methods and Principal Findings

Gingival samples from 23 healthy children, nine children with acute necrotizing gingivitis, and 23 children with acute noma (both healthy and diseased oral sites) were amplified using “universal” PCR primers for the 16 S rRNA gene and pooled according to category (noma, healthy, or acute necrotizing gingivitis), gender, and site status (diseased or control site). Seven libraries were generated. A total of 1237 partial 16 S rRNA sequences representing 339 bacterial species or phylotypes at a 98–99% identity level were obtained. Analysis of bacterial composition and frequency showed that diseased (noma or acute necrotizing gingivitis) and healthy site bacterial communities are composed of similar bacteria, but differ in the prevalence of a limited group of phylotypes. Large increases in counts of Prevotella intermedia and members of the Peptostreptococcus genus are associated with disease. In contrast, no clear-cut differences were found between noma and non-noma libraries.


Similarities between acute necrotizing gingivitis and noma samples support the hypothesis that the disease could evolve from acute necrotizing gingivitis in certain children for reasons still to be elucidated. This study revealed oral microbiological patterns associated with noma and acute necrotizing gingivitis, but no evidence was found for a specific infection-triggering agent.


by Emmanouil Angelakis, Hervé Richet, Jean-Marc Rolain, Bernard La Scola, Didier Raoult


Isolation of Rickettsia species from skin biopsies may be replaced by PCR. We evaluated culture sensitivity compared to PCR based on sampling delay and previous antibiotic treatment.

Methodology/Principal Findings

Skin biopsies and ticks from patients with suspected Rickettsia infection were screened for Rickettsia spp. using qPCR, and positive results were amplified and sequenced for the gltA and ompA genes. Immunofluorescence for spotted fever group rickettsial antigens was done for 79 patients. All skin biopsies and only ticks that tested positive using qPCR were cultured in human embryonic lung (HEL) fibroblasts using the centrifugation-shell vial technique. Patients and ticks were classified as definitely having rickettsioses if there was direct evidence of infection with a Rickettsia sp. using culture or molecular assays or in patients if serology was positive. Data on previous antibiotic treatments were obtained for patients with rickettsiosis. Rickettsia spp. infection was diagnosed in 47 out of 145 patients (32%), 41 by PCR and 12 by culture, whereas 3 isolates were obtained from PCR negative biopsies. For 3 of the patients serology was positive although PCR and culture were negative. Rickettsia africae was the most common detected species (n = 25, [17.2%]) and isolated bacterium (n = 5, [3.4%]). The probability of isolating Rickettsia spp. was 12 times higher in untreated patients and 5.4 times higher in patients from our hometown. Rickettsia spp. was amplified in 24 out of 95 ticks (25%) and we isolated 7 R. slovaca and 1 R. raoultii from Dermacentor marginatus.


We found a positive correlation between the bacteria copies and the isolation success in skin biopsies and ticks. Culture remains critical for strain analysis but is less sensitive than serology and PCR for the diagnosis of a Rickettsia infection.


by Karina M. Monteiro, Mateus B. Cardoso, Cristian Follmer, Nádya P. da Silveira, Daiani M. Vargas, Elliot W. Kitajima, Arnaldo Zaha, Henrique B. Ferreira


Antigen B (AgB) is the major protein secreted by the Echinococcus granulosus metacestode and is involved in key host-parasite interactions during infection. The full comprehension of AgB functions depends on the elucidation of several structural aspects that remain unknown, such as its subunit composition and oligomeric states.

Methodology/Principal Findings

The subunit composition of E. granulosus AgB oligomers from individual bovine and human cysts was assessed by mass spectrometry associated with electrophoretic analysis. AgB8/1, AgB8/2, AgB8/3 and AgB8/4 subunits were identified in all samples analyzed, and an AgB8/2 variant (AgB8/2v8) was found in one bovine sample. The exponentially modified protein abundance index (emPAI) was used to estimate the relative abundance of the AgB subunits, revealing that AgB8/1 subunit was relatively overrepresented in all samples. The abundance of AgB8/3 subunit varied between bovine and human cysts. The oligomeric states formed by E. granulosus AgB and recombinant subunits available, rAgB8/1, rAgB8/2 and rAgB8/3, were characterized by native PAGE, light scattering and microscopy. Recombinant subunits showed markedly distinct oligomerization behaviors, forming oligomers with a maximum size relation of rAgB8/3>rAgB8/2>rAgB8/1. Moreover, the oligomeric states formed by rAgB8/3 subunit were more similar to those observed for AgB purified from hydatid fluid. Pressure-induced dissociation experiments demonstrated that the molecular assemblies formed by the more aggregative subunits, rAgB8/2 and rAgB8/3, also display higher structural stability.


For the first time, AgB subunit composition was analyzed in samples from single hydatid cysts, revealing qualitative and quantitative differences between samples. We showed that AgB oligomers are formed by different subunits, which have distinct abundances and oligomerization properties. Overall, our findings have significantly contributed to increase the current knowledge on AgB expression and structure, highlighting issues that may help to understand the parasite adaptive response during chronic infection.


by Louis-Albert Tchuem Tchuenté, Romuald Isaka Kamwa Ngassam, Laurentine Sumo, Pierre Ngassam, Calvine Dongmo Noumedem, Deguy D'or Luogbou Nzu, Esther Dankoni, Christian Mérimé Kenfack, Nestor Feussom Gipwe, Julie Akame, Ann Tarini, Yaobi Zhang, Fru Fobuzski Angwafo


Schistosomiasis and soil-transmitted helminthiasis (STH) are widely distributed in Cameroon. Although mass drug administration (MDA) of mebendazole is implemented nationwide, treatment with praziquantel was so far limited to the three northern regions and few health districts in the southern part of Cameroon, based on previous mapping conducted 25 years ago. To update the disease distribution map and determine where treatment with praziquantel should be extended, mapping surveys were conducted in three of the seven southern regions of Cameroon, i.e. Centre, East and West.


Parasitological surveys were conducted in April–May 2010 in selected schools in all 63 health districts of the three targeted regions, using appropriate research methodologies, i.e. Kato-Katz and urine filtration.

Principal Findings

The results showed significant variation of schistosomiasis and STH prevalence between schools, villages, districts and regions. Schistosoma mansoni was the most prevalent schistosome species, with an overall prevalence of 5.53%, followed by S. haematobium (1.72%) and S. guineensis (0.14%). The overall prevalence of schistosomiasis across the three regions was 7.31% (95% CI: 6.86–7.77%). The prevalence for Ascaris lumbricoides was 11.48 (95% CI: 10.93–12.04%), Trichuris trichiura 18.22% (95% CI: 17.56–18.90%) and hookworms 1.55% (95% CI: 1.35–1.78%), with an overall STH prevalence of 24.10% (95% CI: 23.36–24.85%) across the three regions. STH was more prevalent in the East region (46.57%; 95% CI: 44.41–48.75%) in comparison to the Centre (25.12; 95% CI: 24.10–26.17%) and West (10.49%; 95% CI: 9.57–11.51%) regions.


In comparison to previous data, the results showed an increase of schistosomiasis transmission in several health districts, whereas there was a significant decline of STH infections. Based on the prevalence data, the continuation of annual or bi-annual MDA for STH is recommended, as well as an extension of praziquantel in identified moderate and high risk communities for schistosomiasis.


by Hope H. Biswas, Oscar Ortega, Aubree Gordon, Katherine Standish, Angel Balmaseda, Guillermina Kuan, Eva Harris


Tens of millions of dengue cases and approximately 500,000 life-threatening complications occur annually. New tools are needed to distinguish dengue from other febrile illnesses. In addition, the natural history of pediatric dengue early in illness in a community-based setting has not been well-defined.


Data from the multi-year, ongoing Pediatric Dengue Cohort Study of approximately 3,800 children aged 2–14 years in Managua, Nicaragua, were used to examine the frequency of clinical signs and symptoms by day of illness and to generate models for the association of signs and symptoms during the early phase of illness and over the entire course of illness with testing dengue-positive. Odds ratios (ORs) and 95% confidence intervals were calculated using generalized estimating equations (GEE) for repeated measures, adjusting for age and gender.


One-fourth of children who tested dengue-positive did not meet the WHO case definition for suspected dengue. The frequency of signs and symptoms varied by day of illness, dengue status, and disease severity. Multivariable GEE models showed increased odds of testing dengue-positive associated with fever, headache, retro-orbital pain, myalgia, arthralgia, rash, petechiae, positive tourniquet test, vomiting, leukopenia, platelets ≤150,000 cells/mL, poor capillary refill, cold extremities and hypotension. Estimated ORs tended to be higher for signs and symptoms over the course of illness compared to the early phase of illness.


Day-by-day analysis of clinical signs and symptoms together with longitudinal statistical analysis showed significant associations with testing dengue-positive and important differences during the early phase of illness compared to the entire course of illness. These findings stress the importance of considering day of illness when developing prediction algorithms for real-time clinical management.

The Wall Street Journal
Merck predicted first-quarter earnings that fell short of Wall Street's targets, citing the impact from fluctuating currencies, but backed its forecast for the full year.
About one in five pilots says sleepiness has caused a serious error on the job, according to a new survey by the National Sleep Foundation.
Late-stage trial results for Merck KGaA's lung-cancer drug Stimuvax won't be available until 2013. The company has a licensing agreement with U.S.-based Oncothyreon, and that company's shares fell on the news.
National Institutes of Health (NIH)
Researchers have developed a method to label transplanted cells so they can be tracked by magnetic resonance imaging (MRI). In the future, as cell therapies become a more integral part of regenerative medicine and tumor treatment, there could be increased need to measure how many transplanted immune or stem cells reach their target.
A new series of monthly health tips, Time to Talk Tips, will provide consumers with easy-to-read information on complementary health practices. The effort is managed by the National Center for Complementary and Alternative Medicine (NCCAM) at the National Institutes of Health.
The New York Times
A retirement community in Virginia reverses a controversial policy excluding disabled residents from a dining room.
National Institutes of Health (NIH)
Notice NOT-TR-12-003 from the NIH Guide for Grants and Contracts
Notice NOT-OD-12-073 from the NIH Guide for Grants and Contracts
Notice NOT-OD-12-069 from the NIH Guide for Grants and Contracts
Notice NOT-OD-12-074 from the NIH Guide for Grants and Contracts
Notice NOT-OD-12-076 from the NIH Guide for Grants and Contracts
Notice NOT-OD-12-070 from the NIH Guide for Grants and Contracts
Notice NOT-OD-12-075 from the NIH Guide for Grants and Contracts
Notice NOT-HS-12-008 from the NIH Guide for Grants and Contracts
The New York Times
With its space-capsule appearance and its tough exterior, kohlrabi may seem daunting. But at its heart, this vegetable is crisp, juicy, versatile and bursting with nutrients.
Using grated kohlrabi rather than spinach gives these two classic preparations a twist.
The Wall Street Journal
Roche exerted pressure on Illumina, claiming it has other options should the U.S. gene decoder keep resisting the Swiss drug maker's hostile $5.7 billion bid.
The New York Times
Letter to the editor.
Letters to the editor.
Letter to the editor.
Organización Mundial de la Salud. Noticias
6 de marzo de 2012 -- El mundo ha cumplido con la meta de los Objetivos de Desarrollo del Milenio (ODM) de reducir a la mitad la proporción de personas sin acceso al agua potable mucho antes de la fecha límite de 2015 , según un informe publicado hoy por UNICEF y la Organización Mundial de la Salud..
Las propiedades medicinales de la marihuana son un tema polémico desde hace tiempo. Sus detractores citan sus efectos negativos en la memoria de trabajo y en la capacidad para retener información durante periodos cortos de tiempo como razones para no emplearla para fines médicos. Estos efectos secundarios son de sobra conocidos, pero ahora un grupo internacional de investigadores ha ampliado el conocimiento que se posee sobre la acción neurobiológica que provoca dichos efectos. Quality validation date: 2012-03-06
Un nuevo estudio a cargo de investigadores nórdicos ha cuestionado la extendida hipótesis de que la última glaciación hiciera desaparecer los bosques escandinavos hasta la llegada, hace unos 9 000 años, de un clima más cálido que habría fundido la placa de hielo. Los hallazgos, publicados en la revista Science, sugieren que algunas coníferas habrían sobrevivido en las cumbres montañosas que sobresalían de la placa de hielo, tanto en zonas litorales como en islas. Por consiguiente, y desviándose de la teoría más aceptada, no todos los árboles que pueblan la región en la actualidad tendrían su origen en una migración de especies tras el deshielo. Quality validation date: 2012-03-06
Cada vez más científicos consideran el grafeno, un alótropo del carbono, el nuevo silicio. Pero también saben que su conductividad es excesiva para poder utilizarse en chips informáticos. Ahora un equipo científico de la Universidad de Mánchester (Reino Unido) podría haber dado con una solución a este problema. Quality validation date: 2012-03-06

Cuts hamper bid to tackle AIDS

Nature 483, 7388 (2012).

Author: Erika Check Hayden

Medics warn of missed chance to use drugs to curb HIV.


A solid case for Majorana fermions

Nature 483, 7388 (2012).

Author: Eugenie Samuel Reich

First compelling evidence of self-annihilating entities in a semiconductor is a step forward for quantum computing.

British Journal of Cancer

Effects of erythropoietin receptors and erythropoiesis-stimulating agents on disease progression in cancer

British Journal of Cancer advance online publication, March 6, 2012. doi:10.1038/bjc.2012.42

Authors: M Aapro, W Jelkmann, S N Constantinescu & B Leyland-Jones