RESUMEN

Controlled radical polymerization of ethylene using different commercially available, cheap, and non-toxic iodo alkyls is performed by iodine transfer polymerization (ITP) under mild conditions (≤100 °C and ≤200 bar). The formed well-defined iodo end-capped polyethylene (PE-I) species is very stable upon storage. Narrow molar-mass distributions (dispersities around 1.6) were obtained up to number average molar masses of 7300 g mol-1 . The ethylene copolymerization by ITP (ITcoP) with vinyl acetate allowed to form a broad range of poly(ethylene-co-vinyl acetate) (EVA) containing from 0 to 85 mol % of VAc unit. In addition, EVA-b-PE block copolymers or EVA-b-EVA gradient block copolymers with different content of VAc in the blocks were obtained for the first time using ITP. Finally, reactivity trends were explored by a theoretical mechanistic study. This highly versatile synthetic platform provides a straightforward access to a diverse range of well-defined PE based polymer materials.

RESUMEN

The register of activity at the Ebola Treatment Center (ETC) in Forecariah (Guinea), from April 23 to June 5, 2015 is presented for analysis. The viral load of each patient is evaluated by the cycle threshold (Ct). One hundred and thirty patients were seen in Triage at the ETC, of which 24 (18.5%) patients who failed to meet theWHO case criteria for viral hemorrhagic fever were excluded from admission to the ETC. Of the 106 patients admitted in the ETC, 72 (67.9%) were declared non-cases after the results of their two PCR (drawn 48 hours apart) tests were negative. Thirty-four patients were tested positive for Ebola virus disease (EVD): 19 women and 15 men (sex ratio: male/female = 0.78), mean age of 33.51 ± 20.1 years (extremes of 42 days to 70 years), of which six children were aged below 8 years. The median initial Ct value was 21.6 ± 6.3 cycles in this group. Enquiry into patient contacts was only able to identify actual contacts in 20 of these patients (58.8%). Thirteen patients were ultimately cured of EVD (six men and seven women) - with a median age of 31.8 years (extremes of 4 to 54 years). These patients presented on admission with a median Ct value of 21.88 ± 6.2 cycles (extremes of 17.6 to 31.7). Of the six children aged below 8 years, only one survived. Twenty-one patients (61.76%) with EVD died (9 men and 12 women) - median age, 34 ± 21 years (extremes of 42 days to 70 years). They presented on admission with a median Ct value of 18 ± 7 cycles (extremes of 12 to 24). The single most important factor associated with lethality was the Ct value at the time of admission to the ETC (P = 0.0004), i.e., the lower the Ct value, the higher the lethality rate or simply stated, the higher the viral load, the greater the lethality. Age, sex, identification of contact, and delay between the onset of symptoms and admission did not prove to be predictive of death outcome in our series.

Asunto(s)

RESUMEN

Ebola virus disease (EVD) is associated with a high lethality rate even when the afflicted are provided with good support in an Ebola treatment center (ETC). Basic laboratory tests can help to better understand the pathophysiology of the disease, to guide treatment and to establish simple protocols and procedures tailored to the practice of medicine in the context of such precarious environment for caregivers. Based on a few clinical cases of patients treated in the ETC of Forecariah, Guinea, run by the French Red Cross, this article describes the difficult conditions associated with the provision of medical practice in this challenging environment, aiming to minimize the casualties in the EVD patient and to train the health staff.

Asunto(s)

RESUMEN

Dengue virus infection is the most frequent arthropod-borne infection affecting humans in the world. Our understanding of the pathophysiological events leading to mild or severe outcomes of the disease remains limited by the fact that viral target cells in the human body are poorly characterized. One of the most sensitive strategies for detecting cells supporting active replication of this positive-strand RNA virus is the search for the replicative intermediate, an antigenome of negative polarity, by RT-PCR. However, a phenomenon described as 'false priming' of the reverse transcriptase (RT) prevents strand-specific detection. The results of the current study showed that this event corresponds to cDNA synthesis that is independent of any primer addition. This property was general to all RNAs tested and was not associated with small free nucleic acids, such as tRNAs and microRNAs. Rather, it corresponded to initiation of cDNA synthesis from the 3' end of the RNA template, and a model is proposed in which the template RNA snaps back upon itself and creates a transient RNA primer suitable for the RT. Such a property would explain why many assays proposed for detection of a replicative intermediate are not specific, and may help in the development of a molecular biology protocol that could allow replication studies of RNA viruses of human interest, such as dengue virus, hepatitis C virus and enteroviruses.

Asunto(s)

RESUMEN

Profiles of enzymatic activities were studied using 19 chromogenic substrates for 22 species (211 strains) belonging to the genera Agrobacterium, Alcaligenes, Alteromonas, Flavobacterium and Pseudomonas. The observed patterns of reactions may be useful as an aid in identification of these species and for epidemiological studies.

Asunto(s)

RESUMEN

Six strains of Kluyvera ascorbata--an unusual species in the family Enterobacteriaceae--were isolated from six healthy lemurs, located in Tananarive's zoological garden. Their bacteriological characters are reported and compared with those of Levinea and Escherichia coli. Their occurrence and significance in animals are discussed.

Asunto(s)

RESUMEN

In addition to capsular antigen typing and biotyping (sorbose, d-tartrate, dulcitol), the epidemiology of Klebsiella oxytoca can be improved by new biochemical characterization. The authors propose to determine tetrathionate-reductase activity, D-melezitose fermentation and brown pigment production onto a mineral gluconate-ferric citrate medium. In order to assess the value of these new markers, several hospital epidemiological surveys were performed in France and Spain (112 strains studied).

Asunto(s)

RESUMEN

A total of 358 Salmonella strains belonging to subspecies I (other than "S. typhisuis") and possessing the 6,7:c:1,5 antigenic factors were studied on the basis of their classical biochemical characters and their subfactors of the H:c antigen. They were classified into 4 homogeneous taxa which can be differentiated by the use of three characters: production of acid from dulcitol and mucate and H2S production. Production of acid from arabinose and trehalose are not reliable markers. The taxonomic level of these four taxa founded on their biochemical characters is that of biovars within one serovar. For practical purposes, we propose to refer to these biovars as Paratyphi C, Choleraesuis sensu stricto, Choleraesuis var. Kunzendorf and Choleraesuis var. Decatur.

Asunto(s)