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1.
Paediatr Anaesth ; 32(7): 815-824, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35332622

RESUMO

BACKGROUND: The validity of current tools for intraoperative objective assessment of nociception/antinociception balance during anesthesia in young and very young surgery children is unknown. AIM: Primary aim of the study was to test the hypothesis that the Newborn Infant Parasympathetic Evaluation (NIPE) index performs better in indicating nociception in anesthetized children below 2 years than changes in heart rate. Secondary aims were to evaluate associations between intraoperative changes in NIPE index values and postoperative pain and emergence delirium. METHODS: Fifty-one children aged <2 years who underwent surgery were included in this prospective observational study. Patients were assigned to either group 1 (healthy children, n = 31) or group 2 (critically ill, ventilated premature infants and neonates, n = 20). The NIPE index and heart rate in response to three defined nociceptive stimuli were continuously recorded. Two different scales, Kindliche Unbehagens- und Schmerzskala (KUS) and Pediatric Anesthesia Emergence Delirium (PAED) as well as a Pain Questionnaire were used to assess postoperative pain levels and emergence delirium. RESULTS: In total, 110 nociceptive events were evaluated. The analysis revealed a statistically significant association between a decrease in the NIPE index and all nociceptive stimuli, with a sensitivity of 92% and a specificity of 96%. The mean percentage decrease ranged from approx. 15%-30% and was highly statistically significant in both groups and for each of the nociceptive events except for venous puncture (p = .004). In contrast, no consistent change in heart rate was demonstrated. The KUS and PAED scale scores were significantly associated with the duration of anesthesia (p = .04), but not with intraoperative NIPE depression. CONCLUSION: The NIPE index was reliable for assessing intraoperative nociception in children aged <2 years and was more reproducible for detecting specific nociceptive stimuli during general anesthesia than heart rate. An effect on postoperative outcome is still elusive.


Assuntos
Delírio do Despertar , Nociceptividade , Anestesia Geral , Criança , Estado Terminal , Delírio do Despertar/diagnóstico , Frequência Cardíaca/fisiologia , Humanos , Lactente , Recém-Nascido , Medição da Dor , Dor Pós-Operatória
2.
Sci Eng Ethics ; 28(2): 12, 2022 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-35258776

RESUMO

Artificial Intelligence (AI) seems to be impacting all industry sectors, while becoming a motor for innovation. The diffusion of AI from the civilian sector to the defense sector, and AI's dual-use potential has drawn attention from security and ethics scholars. With the publication of the ethical guideline Trustworthy AI by the European Union (EU), normative questions on the application of AI have been further evaluated. In order to draw conclusions on Trustworthy AI as a point of reference for responsible research and development (R&D), we approach the diffusion of AI across both civilian and military spheres in the EU. We capture the extent of technological diffusion and derive European and German patent citation networks. Both networks indicate a low degree of diffusion of AI between civilian and defense sectors. A qualitative investigation of project descriptions of a research institute's work in both civilian and military fields shows that military AI applications stress accuracy or robustness, while civilian AI reflects a focus on human-centric values. Our work represents a first approach by linking processes of technology diffusion with normative evaluations of R&D.


Assuntos
Inteligência Artificial , Pesquisa , Humanos
3.
Ergonomics ; 64(5): 553-570, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33228457

RESUMO

In order to investigate differences in comfort and discomfort experiences amongst different regions of the world (America, Asia and Europe), a cross cultural study was performed. A questionnaire was sent to participants out in nine countries (Brazil, Canada, the USA, China, Indonesia, Thailand, Germany, Italy and the Netherlands). In total 795 participants completed the questionnaires. All countries score the comfort of a luxurious bed higher than a simple bed, first-class seats higher than economy class and all countries rate the comfort lower when the duration of sitting increases. The study suggests that in the USA and Canada softer beds, hammocks, more luxurious seats and softer pillows are scored as more comfortable compared with the other countries. There are indications that China and Germany prefer a harder mattress than in the other countries. For pillows, the differences between countries are large, which might show that much is influenced by habitude or hesitation to use something new. The Asian countries score the comfort of a brace neck pillow higher, which might be because these participants better realise the benefits better or feel less concerned to wear something that might give the appearance of an orthotic device. Further studies are needed to confirm these suggestions. The study shows that obvious differences are seen in all countries, which makes the construct of comfort internationally comparable. Practitioner summary: In designing and manufacturing globally, it is important to know how different parts of the world experience (dis)comfort. This study did not show large cultural differences amongst nine countries. Some differences emerge regarding pillows, perhaps as differences in sleeping habits play a role. Abbreviations: MANOVA: multivariate analysis of variance; VDA: Vargha and Delaney's A statistic; USA: United States of America.


Assuntos
Comportamento do Consumidor , Comparação Transcultural , América , Europa (Continente) , Humanos , Itália , Países Baixos , Tailândia , Estados Unidos
4.
Chemistry ; 25(9): 2313-2321, 2019 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-30489662

RESUMO

Carbaboranes 1,2-(EH)2 -closo-1,2-C2 B10 H10 (E=S, Se) were prepared, in the case of E=Se for the first time. Their semi-experimental equilibrium molecular structures were established by the concerted use of quantum-chemical calculations and gas electron diffraction. A method was developed and implemented to quantify the contribution of experimental data to each refined structural parameter. The accuracy of the experimental structures and those calculated at the MP2 level of theory were gauged by comparison of experimental 11 B NMR chemical shifts with quantum-chemically computed values; the inclusion of electron correlation (GIAO-MP2) provided superior results. For the purpose of geometrical prediction, the remaining group 16 elements were considered, and the icosahedral structures for E=O and Te were also computed; for E=O the same theoretical approach was used as for E=S, and for E=Te a description similar to that for E=Se was employed.

5.
Cell Microbiol ; 20(2)2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29156489

RESUMO

The human gastrointestinal tract is a complex ecosystem in which epithelial cells and microorganisms of the intestinal microbiota live in symbiosis. Certain members of the microbiota, in particular Escherichia coli strains of the B2 phylotype, carry the polyketide synthase-island encoding the genotoxin colibactin. Colibactin is a nonribosomal peptide or polyketide-nonribosomal peptide hybrid of still unsolved structure, which induces DNA double strand breaks (DSBs) in eukaryotic cells. However, direct contact between live bacteria and host cell is required in order to elicit these genotoxic effects. In this study, we used a variety of cell culture models, among them, a 3D cell culture approach based on decellularised small intestinal submucosa, to investigate whether the intestinal mucus layer has the potential to interfere with colibactin activity. We demonstrate that the expression of mucins and the formation of an adherent mucus layer significantly increased with increasing complexity of cell culture. Moreover, we show that the presence of an adherent mucus layer on epithelial cells attenuates the genotoxic activity of colibactin, by preventing the induction of DNA-DSBs. Removal of the adherent mucus layer restored the occurrence of DNA-DSBs.


Assuntos
Trato Gastrointestinal/microbiologia , Muco/microbiologia , Mutagênicos/metabolismo , Peptídeos/metabolismo , Policetídeos/metabolismo , Linhagem Celular Tumoral , Dano ao DNA/fisiologia , Escherichia coli/patogenicidade , Microbioma Gastrointestinal/fisiologia , Ilhas Genômicas/fisiologia , Células HT29 , Humanos , Simbiose/fisiologia , Virulência/fisiologia
6.
Angew Chem Int Ed Engl ; 56(29): 8578-8582, 2017 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-28524451

RESUMO

Tris[tetrafluoro-4-(trifluoromethyl)phenyl]borane (BTolF) was prepared by treating boron tribromide with tetrameric F3 CC6 F4 -CuI . The F3 CC6 F4 -CuI was generated from F3 CC6 F4 MgBr and copper(I) bromide. Lewis acidities of BTolF evaluated by the Gutmann-Beckett method and calculated fluoride-ion affinities are 9 and 10 %, respectively, higher than that of tris(pentafluorophenyl)borane (BCF) and even higher than that of SbF5 . The molecular structures of BTolF and BCF were determined by gas-phase electron diffraction, that of BTolF also by single-crystal X-ray diffraction.

7.
Chemphyschem ; 17(10): 1463-7, 2016 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-26865044

RESUMO

Trichloromethyl thiocyanate, CCl3 SCN, was structurally studied in both the gas and crystal phases by means of gas electron diffraction (GED) and single-crystal X-ray diffraction (XRD), respectively. Both experimental studies and quantum chemical calculations indicate a staggered orientation of the CCl3 group relative to the SCN group. This conclusion is supported by the similarity of the C-SCN bond length to that of the anti-structure of CH2 ClSCN (Berrueta Martínez et al. Phys. Chem. Chem. Phys. 2015, 17, 15805-15812). Bond lengths and angles are similar for gas and crystal CCl3 SCN structures; however, the crystal structure presents different intermolecular interactions. These include halogen and chalcogen type interactions, the geometry of which was studied. Characteristic C-Y⋅⋅⋅N angles (Y=Cl or S) close to 180° provide evidence for typical σ-hole interactions along the halogen/chalcogen-carbon bond in N⋅⋅⋅Cl and N⋅⋅⋅S, intermolecular units.

8.
Phys Chem Chem Phys ; 18(1): 393-402, 2016 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-26617390

RESUMO

The molecular structure and conformational properties of 2,2,2-trichloroethyl chloroformate, ClC(O)OCH2CCl3 were determined experimentally using gas-phase electron diffraction (GED) and theoretically based on quantum-chemical calculations at the MP2 and DFT levels of theory. Further experimental measurements such as UV-visible, IR and Raman spectroscopy were complemented with the corresponding theoretical studies. All experimental results and calculations confirm the presence of two conformers namely anti-gauche (C1 symmetry) and anti-anti (Cs symmetry). The conformational preference was rationalised by NBO and AIM analyses. Molecular properties such as ionisation potential, electronegativity, chemical potential, chemical hardness and softness were deduced from HOMO-LUMO analyses. The TD-DFT approach was applied to assign the electronic transitions observed in the UV-visible spectrum. A detailed interpretation of the infrared and Raman spectra of the title compound are reported. Using calculated frequencies as a guide, IR and Raman spectra also provide evidence for the presence of both C1 and Cs conformers.

9.
BMC Cardiovasc Disord ; 16: 132, 2016 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-27283399

RESUMO

BACKGROUND: Osteopontin (OPN) regulates the Ca(++)-deposition in bone and coronary arteries. Elevated OPN were also associated with (aortic) valve calcification in healthy individuals. This study aimed to investigate the association between OPN levels and mitral annulus calcification (MAC) in patients with coronary artery disease (CAD). METHODS: In this cross-sectional study OPN-levels were measured in 223 non-or ex-smoking patients (160 male, mean age: 61,09 ± 11,02 years; 63 female: mean age: 67,49 ± 7,87 years) with CAD. Plasma OPN levels were measured by ELISA and MAC was evaluated by echocardiography. RESULTS: Forward stepwise logistic regression analysis (likelihood quotient) showed significantly higher OPN-levels in patients with MAC compared to patient without calcified mitral annulus independent from the classic risk factors age and severity of coronary artery disease (CAD). In addition to age and the severity of CAD, the circulating OPN amount was a significant predictor for MAC. CONCLUSIONS: This is the first clinical trial which observed increased circulating OPN levels in MAC, suggesting a distinct role of OPN in the process of MAC. Considering the current knowledge about OPN it is more likely that OPN does not promote but counteracts valve calcification and therefore is elevated in course of a calcification processes.


Assuntos
Calcinose/sangue , Doença da Artéria Coronariana/sangue , Estenose Coronária/sangue , Doenças das Valvas Cardíacas/sangue , Osteopontina/sangue , Idoso , Biomarcadores/sangue , Calcinose/diagnóstico por imagem , Estudos de Casos e Controles , Doença da Artéria Coronariana/diagnóstico por imagem , Estenose Coronária/diagnóstico por imagem , Estudos Transversais , Ecocardiografia , Ensaio de Imunoadsorção Enzimática , Feminino , Doenças das Valvas Cardíacas/diagnóstico por imagem , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Índice de Gravidade de Doença , Regulação para Cima
10.
J Phys Chem A ; 120(15): 2420-30, 2016 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-27023801

RESUMO

The coexistence of two conformers in perfluoropropanoyl fluoride, CF3CF2C(O)F, differing in the CC-CF dihedral angle (gauche 85(10)% and anti 15(10)%), has been determined by means of gas-phase electron diffraction (GED). Quantum-chemical calculations performed at the MP2 and B3LYP approximations and cc-pVTZ basis sets reproduce the experimental values with confidence. By contrast, FTIR spectra give no clear evidence for the anti-conformer in the gas phase. Information on this less abundant but stable rotamer is obtained from matrix-isolation/FTIR spectroscopy and liquid Raman spectroscopy. In situ crystallization and single-crystal X-ray diffraction (XRD) data reveal the presence of solely the gauche-conformation in the solid state. A set of intermolecular interactions including C═O···C═O, C-F···F-C, and F···C═O is detected. The nature of bonding and the relative stabilities of gauche- and anti-conformers are explored using natural bond orbitals.

11.
J Am Chem Soc ; 137(1): 126-9, 2015 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-25531826

RESUMO

Starting from ferrocene, pentafluoroferrocene [Fe(C5F5)(C5H5)] can be prepared in five steps via a one-pot lithiation-electrophilic fluorination strategy. Pentafluoroferrocene was characterized by multinuclear NMR and IR spectroscopy, by cyclovoltammetry as well as X-ray (solid) and electron diffraction (gas) and the experimental results compared with DFT calculations.

12.
Chemistry ; 21(35): 12436-48, 2015 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-26213228

RESUMO

Directed tridentate Lewis acids based on the 1,3,5-trisilacyclohexane skeleton with three ethynyl groups [CH2Si(Me)(C2H)]3 were synthesised and functionalised by hydroboration with HB(C6F5)2, yielding the ethenylborane {CH2Si(Me)[C2H2B(C6F5)2]}3, and by metalation with gallium and indium organyls affording {CH2Si(Me)[C2M(R)2]}3 (M = Ga, In, R = Me, Et). In the synthesis of the backbone the influence of substituents (MeO, EtO and iPrO groups at Si) on the orientation of the methyl group was studied with the aim to increase the abundance of the all-cis isomer. New compounds were identified by elemental analyses, multi-nuclear NMR spectroscopy and in some cases by IR spectroscopy. Crystal structures were obtained for cis-trans-[CH2Si(Me)(Cl)]3, all-cis-[CH2Si(Me)(H)]3, all-cis-[CH2Si(Me)(C2H)]3, cis-trans-[CH2Si(Me)(C2H)]3 and all-cis-[CH2Si(Me)(C2SiMe3)]3. A gas-phase electron diffraction experiment for all-cis-[CH2Si(Me)(C2H)]3 provides information on the relative stabilities of the all-equatorial and all-axial form; the first is preferred in both solid and gas phase. The gallium-based Lewis acid {CH2Si(Me)[C2Ga(Et)2]}3 was reacted with a tridentate Lewis base (1,3,5-trimethyl-1,3,5-triazacyclohexane) in an NMR titration experiment. The generated host-guest complexes involved in the equilibria during this reaction were identified by DOSY NMR spectroscopy by comparing measured diffusion coefficients with those of the suitable reference compounds of same size and shape.

13.
Chemistry ; 21(29): 10436-42, 2015 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-26095109

RESUMO

The gas-phase molecular structure of (CH3 )3 CSNO was investigated by using electron diffraction, allowing the first experimental geometrical parameters for an S-nitrosothiol species to be elucidated. Depending on the orientation of the -SNO group, two conformers (anti and syn) are identified in the vapor of (CH3 )3 CSNO at room temperature, the syn conformer being less abundant. The conformational landscape is further scrutinized by using vibrational spectroscopy techniques, including gas-phase and matrix-isolation IR spectroscopy, resulting in a contribution of ca. 80:20 for the anti:syn abundance ratio, in good agreement with the computed value at the MP2(full)/cc-pVTZ level of approximation. The UV/Vis and resonance Raman spectra also show the occurrence of the conformational equilibrium in the liquid phase, with a moderate post-resonance Raman signature associated with the 350 nm electronic absorption.

14.
Inorg Chem ; 54(24): 11868-74, 2015 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-26625008

RESUMO

Because of the comparable electron scattering abilities of carbon and boron, the electron diffraction structure of the C2v-symmetric molecule closo-1,2-C2B10H12 (1), one of the building blocks of boron cluster chemistry, is not as accurate as it could be. On that basis, we have prepared the known diiodo derivative of 1, 9,12-I2-closo-1,2-C2B10H10 (2), which has the same point-group symmetry as 1 but in which the presence of iodine atoms, with their much stronger ability to scatter electrons, ensures much better structural characterization of the C2B10 icosahedral core. Furthermore, the influence on the C2B10 geometry in 2 of the antipodally positioned iodine substituents with respect to both carbon atoms has been examined using the concerted application of gas electron diffraction and quantum chemical calculations at the MP2 and density functional theory (DFT) levels. The experimental and computed molecular geometries are in good overall agreement. Molecular dynamics simulations used to obtain vibrational parameters, which are needed for analyzing the electron diffraction data, have been performed for the first time for this class of compound. According to DFT calculations at the ZORA-SO/BP86 level, the (11)B chemical shifts of the boron atoms to which the iodine substituents are bonded are dominated by spin-orbit coupling. Magnetically induced currents within 2 have been calculated and compared to those for [B12H12](2-), the latter adopting a regular icosahedral structure with Ih point-group symmetry. Similar total current strengths are found but with a certain anisotropy, suggesting that spherical aromaticity is present; electron delocalization in the plane of the hetero atoms in 2 is slightly hindered compared to that for [B12H12](2-), presumably because of the departure from ideal icosahedral symmetry.

15.
Chemistry ; 20(40): 12962-73, 2014 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-25156478

RESUMO

The halogenotrinitromethanes FC(NO2 )3 (1), BrC(NO2 )3 (2), and IC(NO2)3 (3) were synthesized and fully characterized. The molecular structures of 1-3 were determined in the crystalline state by X-ray diffraction, and gas-phase structures of 1 and 2 were determined by electron diffraction. The Hal-C bond lengths in F-, Cl-, and Br-C(NO2 )3 in the crystalline state are similar to those in the gas phase. The obtained experimental data are interpreted in terms of Natural Bond Orbitals (NBO), Atoms in Molecules (AIM), and Interacting Quantum Atoms (IQA) theories. All halogenotrinitromethanes show various intra- and intermolecular non-bonded interactions. Intramolecular N⋅⋅⋅O and Hal⋅⋅⋅O (Hal=F (1), Br (2), I (3)) interactions, both competitors in terms of the orientation of the nitro groups by rotation about the C-N bonds, lead to a propeller-type twisting of these groups favoring the mentioned interactions. The origin of the unusually short Hal-C bonds is discussed in detail. The results of this study are compared to the molecular structure of ClC(NO2 )3 and the respective interactions therein.

16.
J Phys Chem A ; 117(11): 2383-99, 2013 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-23414067

RESUMO

Chlorocarbonylthio- and isothiocyanate (ClC(O)SCN and ClC(O)NCS) have been isolated and characterized by IR (Ar matrix, gas), Raman (liquid), (13)C NMR and UV-visible spectroscopies. Vibrational and quantum chemical studies suggest the presence of the syn and anti conformers (SCN group with respect to the C═O bond) in the gas phase for both constitutional isomers. syn-ClC(O)SCN is preferred by ΔH° (anti/syn) = 1.3(0.3) kcal mol(-1). The solid-state structure of ClC(O)SCN has been determined by single crystal X-ray diffraction analysis at low temperature. The crystalline solid consists exclusively of molecules in the syn conformation. On the other hand, the anti form is more stable for the ClC(O)NCS isomer. The structure of ClC(O)NCS and its conformational composition were determined by gas electron diffraction. An unusual low syn → anti interconversion energy barrier of 0.98 (0.15) kcal mol(-1) was detected for ClC(O)NCS at cryogenic temperatures. The photochemistry of both constitutional isomers isolated in solid argon at 15 K was studied. Rearrangement of ClC(O)SCN to ClC(O)NCS was observed in the neat liquid and under UV-vis irradiation of ClC(O)SCN isolated in solid argon. Properties have been discussed in terms of the valence electronic structure, including the analysis of the He(I) photoelectron spectrum of ClC(O)SCN.

17.
Int J Mach Learn Cybern ; 14(1): 135-150, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35432623

RESUMO

In many cases of machine learning, research suggests that the development of training data might have a higher relevance than the choice and modelling of classifiers themselves. Thus, data augmentation methods have been developed to improve classifiers by artificially created training data. In NLP, there is the challenge of establishing universal rules for text transformations which provide new linguistic patterns. In this paper, we present and evaluate a text generation method suitable to increase the performance of classifiers for long and short texts. We achieved promising improvements when evaluating short as well as long text tasks with the enhancement by our text generation method. Especially with regard to small data analytics, additive accuracy gains of up to 15.53% and 3.56% are achieved within a constructed low data regime, compared to the no augmentation baseline and another data augmentation technique. As the current track of these constructed regimes is not universally applicable, we also show major improvements in several real world low data tasks (up to +4.84 F1-score). Since we are evaluating the method from many perspectives (in total 11 datasets), we also observe situations where the method might not be suitable. We discuss implications and patterns for the successful application of our approach on different types of datasets.

18.
Nat Commun ; 14(1): 7660, 2023 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-37996412

RESUMO

Transmission of Trypanosoma brucei by tsetse flies involves the deposition of the cell cycle-arrested metacyclic life cycle stage into mammalian skin at the site of the fly's bite. We introduce an advanced human skin equivalent and use tsetse flies to naturally infect the skin with trypanosomes. We detail the chronological order of the parasites' development in the skin by single-cell RNA sequencing and find a rapid activation of metacyclic trypanosomes and differentiation to proliferative parasites. Here we show that after the establishment of a proliferative population, the parasites enter a reversible quiescent state characterized by slow replication and a strongly reduced metabolism. We term these quiescent trypanosomes skin tissue forms, a parasite population that may play an important role in maintaining the infection over long time periods and in asymptomatic infected individuals.


Assuntos
Parasitos , Trypanosoma brucei brucei , Trypanosoma , Moscas Tsé-Tsé , Animais , Humanos , Trypanosoma brucei brucei/genética , Pele/parasitologia , Moscas Tsé-Tsé/parasitologia , Mamíferos
19.
Inf Syst Front ; : 1-23, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36311478

RESUMO

In crises such as the COVID-19 pandemic, it is crucial to support users when dealing with social media content. Considering digital resilience, we propose a web app based on Social Network Analysis (SNA) to provide an overview of potentially misleading vs. non-misleading content on Twitter, which can be explored by users and enable foundational learning. The latter aims at systematically identifying thematic patterns which may be associated with misleading information. Additionally, it entails reflecting on indicators of misleading tweets which are proposed to approach classification of tweets. Paying special attention to non-expert users of social media, we conducted a two-step Think Aloud study for evaluation. While participants valued the opportunity to generate new knowledge and the diversity of the application, qualities such as equality and rapidity may be further improved. However, learning effects outweighed individual costs as all users were able to shift focus onto relevant features, such as hashtags, while readily pointing out content characteristics. Our design artifact connects to learning-oriented interventions regarding the spread of misleading information and tackles information overload by a SNA-based plug-in.

20.
Elife ; 102021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34355698

RESUMO

African trypanosomes cause sleeping sickness in humans and nagana in cattle. These unicellular parasites are transmitted by the bloodsucking tsetse fly. In the mammalian host's circulation, proliferating slender stage cells differentiate into cell cycle-arrested stumpy stage cells when they reach high population densities. This stage transition is thought to fulfil two main functions: first, it auto-regulates the parasite load in the host; second, the stumpy stage is regarded as the only stage capable of successful vector transmission. Here, we show that proliferating slender stage trypanosomes express the mRNA and protein of a known stumpy stage marker, complete the complex life cycle in the fly as successfully as the stumpy stage, and require only a single parasite for productive infection. These findings suggest a reassessment of the traditional view of the trypanosome life cycle. They may also provide a solution to a long-lasting paradox, namely the successful transmission of parasites in chronic infections, despite low parasitemia.


Assuntos
Estágios do Ciclo de Vida/fisiologia , Trypanosoma brucei brucei , Animais , Feminino , Trato Gastrointestinal/parasitologia , Interações Hospedeiro-Parasita/fisiologia , Masculino , Proteínas de Protozoários/metabolismo , RNA Mensageiro/metabolismo , RNA de Protozoário/metabolismo , Trypanosoma brucei brucei/patogenicidade , Trypanosoma brucei brucei/fisiologia , Moscas Tsé-Tsé/parasitologia
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