A Milky Way-like barred spiral galaxy at a redshift of 3.

The majority of massive disk galaxies in the local Universe show a stellar barred structure in their central regions, including our Milky Way1,2. Bars are supposed to develop in dynamically cold stellar disks at low redshift, as the strong gas turbulence typical of disk galaxies at high redshift suppresses or delays bar formation3,4. Moreover, simulations predict bars to be almost absent beyond z = 1.5 in the progenitors of Milky Way-like galaxies5,6. Here we report observations of ceers-2112, a barred spiral galaxy at redshift zphot ≈ 3, which was already mature when the Universe was only 2 Gyr old. The stellar mass (M★ = 3.9 × 109 M⊙) and barred morphology mean that ceers-2112 can be considered a progenitor of the Milky Way7-9, in terms of both structure and mass-assembly history in the first 2 Gyr of the Universe, and was the closest in mass in the first 4 Gyr. We infer that baryons in galaxies could have already dominated over dark matter at z ≈ 3, that high-redshift bars could form in approximately 400 Myr and that dynamically cold stellar disks could have been in place by redshift z = 4-5 (more than 12 Gyrs ago)10,11.

Correction: Analysis of local molecular motions of aromatic sidechains in proteins by 2D and 3D fast MAS NMR spectroscopy and quantum mechanical calculations.

Correction for 'Analysis of local molecular motions of aromatic sidechains in proteins by 2D and 3D fast MAS NMR spectroscopy and quantum mechanical calculations' by Piotr Paluch et al., Phys. Chem. Chem. Phys., 2015, 17, 28789-28801.

Improving dipolar recoupling for site-specific structural and dynamics studies in biosolids NMR: windowed RN-symmetry sequences.

Experimental characterization of one-bond heteronuclear dipolar couplings is essential for structural and dynamics characterization of molecules by solid-state NMR. Accurate measurement of heteronuclear dipolar tensor parameters in magic-angle spinning NMR requires that the recoupling sequences efficiently reintroduce the desired heteronuclear dipolar coupling term, fully suppress other interactions (such as chemical shift anisotropy and homonuclear dipolar couplings), and be insensitive to experimental imperfections, such as radio frequency (rf) field mismatch. In this study, we demonstrate that the introduction of window delays into the basic elements of a phase-alternating R-symmetry (PARS) sequence results in a greatly improved protocol, termed windowed PARS (wPARS), which yields clean dipolar lineshapes that are unaffected by other spin interactions and are largely insensitive to experimental imperfections. Higher dipolar scaling factors can be attained in this technique with respect to PARS, which is particularly useful for the measurement of relatively small dipolar couplings. The advantages of wPARS are verified experimentally on model molecules N-acetyl-valine (NAV) and a tripeptide Met-Leu-Phe (MLF). The incorporation of wPARS into 3D heteronuclear or homonuclear correlation experiments permits accurate site-specific determination of dipolar tensors in proteins, as demonstrated on dynein light chain 8 (LC8). Through 3D wPARS recoupling based spectroscopy we have determined both backbone and side chain dipolar tensors in LC8 in a residue-resolved manner. We discuss these in the context of conformational dynamics of LC8. We have addressed the effect of paramagnetic relaxant Cu(ii)-EDTA doping on the dipolar coupling parameters in LC8 and observed no significant differences with respect to the neat sample permitting fast data collection. Our results indicate that wPARS is advantageous with respect to the windowless version of the sequence and is applicable to a broad range of systems including but not limited to biomolecules.

Conserved determinants of lentiviral genome dimerization.

BACKGROUND: Retroviruses selectively package two copies of their unspliced genomes by what appears to be a dimerization-dependent RNA packaging mechanism. Dimerization of human immunodeficiency virus Type-1 (HIV-1) genomes is initiated by "kissing" interactions between GC-rich palindromic loop residues of a conserved hairpin (DIS), and is indirectly promoted by long-range base pairing between residues overlapping the gag start codon (AUG) and an upstream Unique 5' element (U5). The DIS and U5:AUG structures are phylogenetically conserved among divergent retroviruses, suggesting conserved functions. However, some studies suggest that the DIS of HIV-2 does not participate in dimerization, and that U5:AUG pairing inhibits, rather than promotes, genome dimerization. We prepared RNAs corresponding to native and mutant forms of the 5' leaders of HIV-1 (NL4-3 strain), HIV-2 (ROD strain), and two divergent strains of simian immunodeficiency virus (SIV; cpz-TAN1 and -US strains), and probed for potential roles of the DIS and U5:AUG base pairing on intrinsic and NC-dependent dimerization by mutagenesis, gel electrophoresis, and NMR spectroscopy. RESULTS: Dimeric forms of the native HIV-2 and SIV leaders were only detectable using running buffers that contained Mg(2+), indicating that these dimers are more labile than that of the HIV-1 leader. Mutations designed to promote U5:AUG base pairing promoted dimerization of the HIV-2 and SIV RNAs, whereas mutations that prevented U5:AUG pairing inhibited dimerization. Chimeric HIV-2 and SIV leader RNAs containing the dimer-promoting loop of HIV-1 (DIS) exhibited HIV-1 leader-like dimerization properties, whereas an HIV-1NL4-3 mutant containing the SIVcpzTAN1 DIS loop behaved like the SIVcpzTAN1 leader. The cognate NC proteins exhibited varying abilities to promote dimerization of the retroviral leader RNAs, but none were able to convert labile dimers to non-labile dimers. CONCLUSIONS: The finding that U5:AUG formation promotes dimerization of the full-length HIV-1, HIV-2, SIVcpzUS, and SIVcpzTAN1 5' leaders suggests that these retroviruses utilize a common RNA structural switch mechanism to modulate function. Differences in native and NC-dependent dimerization propensity and lability are due to variations in the compositions of the DIS loop residues rather than other sequences within the leader RNAs. Although NC is a well-known RNA chaperone, its role in dimerization has the hallmarks of a classical riboswitch.

Analysis of local molecular motions of aromatic sidechains in proteins by 2D and 3D fast MAS NMR spectroscopy and quantum mechanical calculations.

We report a new multidimensional magic angle spinning NMR methodology, which provides an accurate and detailed probe of molecular motions occurring on timescales of nano- to microseconds, in sidechains of proteins. The approach is based on a 3D CPVC-RFDR correlation experiment recorded under fast MAS conditions (ν(R) = 62 kHz), where (13)C-(1)H CPVC dipolar lineshapes are recorded in a chemical shift resolved manner. The power of the technique is demonstrated in model tripeptide Tyr-(d)Ala-Phe and two nanocrystalline proteins, GB1 and LC8. We demonstrate that, through numerical simulations of dipolar lineshapes of aromatic sidechains, their detailed dynamic profile, i.e., the motional modes, is obtained. In GB1 and LC8 the results unequivocally indicate that a number of aromatic residues are dynamic, and using quantum mechanical calculations, we correlate the molecular motions of aromatic groups to their local environment in the crystal lattice. The approach presented here is general and can be readily extended to other biological systems.

RF inhomogeneity and how it controls CPMAS.

In this report we discuss the effect of radiofrequency field (RF) inhomogeneity on cross-polarization (CP) under magic-angle spinning (MAS) by reviewing the dependence of the CP-detected signal intensity as a function of the position in the sample space. We introduce a power-function model to quantify the position-dependent RF-amplitude profile. The applicability of this model is experimentally verified by nutation spectra obtained by direct signal detection, as well as by CPMAS signal detection, in two commercial MAS probes with different degrees of RF inhomogeneity. A conclusion is that substantial sections of a totally filled rotor, even in a probe with rather good homogeneity, do not contribute at all to the detected spectra. The consequence is that in CPMAS-based recoupling experiments, such as the CP-with-variable-contact-time (CPVC), spatial selectivity of the Hartmann-Hahn matching condition overcomes complications that could be caused by RF inhomogeneity permitting determination of accurate spectral parameters even in cases with high inhomogeneity.

Accurate measurement of heteronuclear dipolar couplings by phase-alternating R-symmetry (PARS) sequences in magic angle spinning NMR spectroscopy.

We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear (1)H-X (X = (13)C, (15)N, (31)P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the (1)H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the (1)H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from (1)H chemical shift anisotropy, while keeping the (1)H-X dipolar couplings intact. Another advantage over conventional DIPSHIFT experiments, which require the signal to be detected in the form of a reduced-intensity Hahn echo, is that the series of π pulses refocuses the X chemical shift and avoids the necessity of echo formation. PARS permits determination of accurate dipolar couplings in a single experiment; it is suitable for a wide range of MAS conditions including both slow and fast MAS frequencies; and it assures dipolar truncation from the remote protons. The performance of PARS is tested on two model systems, [(15)N]-N-acetyl-valine and [U-(13)C,(15)N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate (1)H-(15)N dipolar couplings in the context of 3D experiments is presented on U-(13)C,(15)N-enriched dynein light chain protein LC8.

A Magic-Angle Spinning NMR Method for the Site-Specific Measurement of Proton Chemical-Shift Anisotropy in Biological and Organic Solids.

Proton chemical shifts are a rich probe of structure and hydrogen bonding environments in organic and biological molecules. Until recently, measurements of 1H chemical shift tensors have been restricted to either solid systems with sparse proton sites or were based on the indirect determination of anisotropic tensor components from cross-relaxation and liquid-crystal experiments. We have introduced an MAS approach that permits site-resolved determination of CSA tensors of protons forming chemical bonds with labeled spin-1/2 nuclei in fully protonated solids with multiple sites, including organic molecules and proteins. This approach, originally introduced for the measurements of chemical shift tensors of amide protons, is based on three RN-symmetry based experiments, from which the principal components of the 1H CS tensor can be reliably extracted by simultaneous triple fit of the data. In this article, we expand our approach to a much more challenging system involving aliphatic and aromatic protons. We start with a review of the prior work on experimental-NMR and computational-quantum-chemical approaches for the measurements of 1H chemical shift tensors and for relating these to the electronic structures. We then present our experimental results on U-13C,15N-labeled histdine demonstrating that 1H chemical shift tensors can be reliably determined for the 1H15N and 1H13C spin pairs in cationic and neutral forms of histidine. Finally, we demonstrate that the experimental 1H(C) and 1H(N) chemical shift tensors are in agreement with Density Functional Theory calculations, therefore establishing the usefulness of our method for characterization of structure and hydrogen bonding environment in organic and biological solids.

Multidimensional magic angle spinning NMR spectroscopy for site-resolved measurement of proton chemical shift anisotropy in biological solids.

The proton chemical shift (CS) tensor is a sensitive probe of structure and hydrogen bonding. Highly accurate quantum-chemical protocols exist for computation of (1)H magnetic shieldings in the various contexts, making proton chemical shifts potentially a powerful predictor of structural and electronic properties. However, (1)H CS tensors are not yet widely used in protein structure calculation due to scarcity of experimental data. While isotropic proton shifts can be readily measured in proteins even in the solid state, determination of the (1)H chemical shift anisotropy (CSA) tensors remains challenging, particularly in molecules containing multiple proton sites. We present a method for site-resolved measurement of amide proton CSAs in fully protonated solids under magic angle spinning. The approach consists of three concomitant 3D experiments yielding spectra determined by either mainly (1)H CSA, mainly (1)H­(15)N dipolar, or combined (1)H CSA and (1)H­(15)N dipolar interactions. The anisotropic interactions are recoupled using RN-sequences of appropriate symmetry, such as R12(1)(4), and (15)N/(13)C isotropic CS dimensions are introduced via a short selective (1)H­(15)N cross-polarization step. Accurate (1)H chemical shift tensor parameters are extracted by simultaneous fit of the lineshapes recorded in the three spectra. An application of this method is presented for an 89-residue protein, U-(13)C,(15)N-CAP-Gly domain of dynactin. The CSA parameters determined from the triple fits correlate with the hydrogen-bonding distances, and the trends are in excellent agreement with the prior solution NMR results. This approach is generally suited for recording proton CSA parameters in various biological and organic systems, including protein assemblies and nucleic acids.

Non-Destructive Assessment of the Dynamic Elasticity Modulus of Eucalyptus nitens Timber Boards.

Eucalyptus nitens is a fast-growing wood species with a relevant presence in countries like Australia and Chile. The sustainable construction goals have driven the search of structural applications for Eucalyptus nitens; however, this process has been complicated due to the defects usually presented in these timber boards. This study aims to evaluate the dynamic elasticity modulus (Exd) of Eucalyptus nitens timber boards through non-destructive vibration-based tests. Thirty-six timber boards with different levels of knots and cracks were instrumented and tested in a simply supported condition by measuring longitudinal and transverse vibrations. In the first stage, the Exd was calculated globally through simplified normative formulas. Then, in a second stage, the local variability of the Exd was estimated using operational modal analysis (OMA), finite element numerical simulations (FEM), and regional sensitivity analysis (RSA). The positive correlation found between the global static modulus of elasticity and Exd suggests that non-destructive techniques could be used as a reliable and fast alternative for the assessment of bending stiffness. Finally, the proposed method to estimate the local variability of Exdt based on the combination of OMA, FEM, and RSA techniques was useful to improve the structural selection process of timber boards for lightweight social housing floors.

Clinical characteristics of older patients with COVID-19: a systematic review of case reports.

In the context of the current COVID-19 pandemic, higher morbidity and mortality have been reported in older adults. This age group presents physiological changes and its own clinical conditions such as frailty, dementia, among others. OBJECTIVE: To describe the characteristics of COVID-19 patients, both over and under 80 years old, by conducting a systematic review of the literature describing case reports, and to summarize and critically assess these characteristics. METHODS: Systematic review. The study was registered on the Registry of Health Research Projects (PRISA) of the Peruvian National Institute of Health (code EI00000631). Five electronic databases (Scopus, PubMed, PubMed Central, LILACS, and SCIELO) were systematically searched during the period between December 31, 2019 and April 16, 2020. The search focused on case reports, case studies, and case series of older people with COVID-19 infection aged over or under 80 years. When selecting the cases, priority was given to clinical and epidemiological profile, laboratory and imaging patterns, and comprehensive geriatric evaluation. RESULTS: 1,149 articles were identified; after applying the filters, a total of 15 publications of case reports and complete records of 27 older adults were obtained. The most frequent age group was between 60 to 69 years old. There is little literature regarding case reports of older adults aged over 80 years. The most frequent parameters were hypertension, fever, cough, respiratory distress, ground-glass opacification in chest radiography and tomography. Furthermore, decrease in PaO2/FiO2 ratio and lymphocytes, and increase in C-reactive protein and Interleukin 6 were observed. CONCLUSIONS: This systematic review found little available information of patients under 80 years old, and far less for those over 80 years old, and an absence of comprehensive geriatric assessment.

No contexto da atual pandemia de covid-19, maior morbidade e mortalidade têm sido relatadas em idosos. Sabe-se que essa faixa etária apresenta alterações fisiológicas e condições clínicas próprias, como fragilidade, demência, entre outras. OBJETIVO: Descrever as características de pacientes com covid-19, maiores e menores de 80 anos, por meio de uma revisão sistemática da literatura que descreve relatos de casos, e resumir e avaliar criticamente essas características. MÉTODO: Revisão sistemática. O estudo foi registrado no Registro de Projetos de Pesquisa em Saúde (PRISA) do Instituto Nacional de Saúde do Peru (código EI00000631). Local: cinco bases de dados eletrônicas (Scopus, PubMed, PubMed Central, LILACS e SCIELO) foram sistematicamente pesquisadas entre 31 de dezembro de 2019 e 16 de abril de 2020. A busca se concentrou em relatos de caso, estudos de caso e séries de casos mais antigos pessoas com infecção por SARS-CoV-2 com mais e menos de 80 anos. Na seleção dos casos, a prioridade foi dada ao perfil clínico e epidemiológico, padrões laboratoriais e de imagem, e avaliação geriátrica abrangente. RESULTADOS: Foram identificados 1.149 artigos. Após a aplicação dos filtros, obteve-se um total de 15 publicações de relatos de caso e registros completos de 27 idosos. A faixa etária mais frequente foi de 60 a 69 anos. Há pouca literatura sobre relatos de casos de adultos com mais de 80 anos. Os parâmetros mais frequentes foram hipertensão, febre, tosse, dificuldade respiratória, vidro fosco na radiografia e tomografia de tórax. Também foram observados diminuição da PaO2 / FiO2 e linfócitos, e aumento da proteína C reativa e Interleucina 6. CONCLUSÕES: Esta revisão sistemática encontrou poucas informações disponíveis sobre pacientes com menos de 80 anos, em quantidade ainda menor para aqueles com mais de 80 anos, além de uma ausência de avaliação geriátrica abrangente.

The application of 23Na double-quantum-filter (DQF) NMR spectroscopy for the study of spinal disc degeneration.

Degenerative disc disease is an irreversible process that leads to a loss of mechanical integrity and back pain in millions of people. In this report, (23)Na double-quantum-filtered (DQF) NMR spectroscopy is used to study disc tissues in two stages of degeneration. Initial results indicate that the (23)Na DQF signal may be useful for determining the degree of degeneration. The spectral analysis reveals the presence of sodium environments with different residual quadrupolar couplings and T(2) relaxation times that we attribute to different regions, or compartments, corresponding to different biochemical regions in the tissue. In general it is found that there are compartments with no residual quadrupolar couplings, compartments with moderate couplings (200 to 1000 Hz), and compartments with couplings ranging from 1500 to 3000 Hz. The results indicate that (23)Na DQF NMR spectroscopy provides a probe of the degenerative state of the intervertebral disc tissues, and might hold potential as a novel diagnostic method for detection of disc degeneration.

The relationship between 207Pb NMR chemical shift and solid-state structure in Pb(II) compounds.

The analysis of heavy-metal solids with NMR spectroscopy provides a means of investigating the electronic environment through the dependence of the chemical shift on structure. We have investigated the relation of the 207Pb NMR isotropic chemical shift, span, and skew of a series of solid Pb(II) compounds to lattice parameters. Complementary relativistic spin-orbit density functional calculations on clusters such as PbI64- that model the local environment in the dihalides show a dependence of NMR properties on the local structure in good agreement with experimental results.

New UV-source catalogs, UV spectral database, UV variables and science tools from the GALEX surveys.

We present a new, expanded and improved catalog of Ultraviolet (UV) sources from the GALEX All-Sky Imaging survey: GUVcat_AIS (Bianchi et al. in Astrophys. J. Suppl. Ser. 230:24, 2017). The catalog includes 83 million unique sources (duplicate measurements and rim artifacts are removed) measured in far-UV and near-UV. With respect to previous versions (Bianchi et al. in Mon. Not. R. Astron. Soc. 411:2770 2011a, Adv. Space Res. 53:900-991, 2014), GUVcat_AIS covers a slightly larger area, 24,790 square degrees, and includes critical corrections and improvements, as well as new tags, in particular to identify sources in the footprint of extended objects, where pipeline source detection may fail and custom-photometry may be necessary. The UV unique-source catalog facilitates studies of density of sources, and matching of the UV samples with databases at other wavelengths. We also present first results from two ongoing projects, addressing respectively UV variability searches on time scales from seconds to years by mining the GALEX photon archive, and the construction of a database of ∼120,000 GALEX UV spectra (range ∼1300-3000 Å), including quality and calibration assessment and classification of the grism, hence serendipitous, spectral sources.

Proceso de vacunación contra el COVID-19 y los retos que enfrenta Colombia / COVID-19 Vaccination Process and the Challenges Colombia Faces / Processo de vacinação contra COVID-19 e os desafios que encara a Colômbia

La vacunación se activó en el mundo como la principal medida de contención de la pandemia ocasionada por el COVID-19. Para Colombia, se establecieron cinco etapas y dos fases en las que se priorizó la aplicación de los biológicos según grupos de edad y perfiles de riesgo. Según cifras oficiales del Ministerio de Salud, durante la primera etapa, que dio inicio el 17 de febrero del 2021, se inmunizaron 1.453.432 personas; en la segunda, 6.620.274; en la tercera, 9.325.861; en la cuarta, 8.436.318 y durante la quinta etapa, al 15 de julio, ya había 15.750.703 personas vacunadas.Se estima que para el 21 de diciembre del año 2022, se culmine la fase 1 de vacunación, que tiene que ver con las dosis de refuerzo de la población mayor de cincuenta años, una vez se hayan cumplido cuatro meses de la aplicación de la segunda dosis, para luego avanzar en la fase 2.El Plan Nacional de Vacunación contra el COVID-19 en la primera fase buscó reducir la mortalidad y la incidencia de casos graves por este virus, así como proteger a los trabajadores de la salud. En la segunda fase, se enfoca en reducir el contagio y generar inmunidad de rebaño

Vaccination was activated worldwide as the main measure to contain the COVID-19 pandemic. For Colombia, five stages and two phases were established in which vaccine administration was prioritized according to age groups and risk profiles. According to official figures from the Colombian Ministry of Health, during the first stage, which began on February 17, 2021, 1,453,432 people were immunized; in the second, 6,620,274; in the third, 9,325,861; in the fourth, 8,436,318, and during the fifth stage, as of July 15, 15,750,703 people had already been vaccinated. It is estimated that by December 21, 2022, phase 1 of vaccination, which has to do with booster doses for the population over 50 years of age, will be completed four months after administering the second dose, and then move on to phase 2.The National COVID-19 Vaccination Plan sought to reduce mortality and the incidence of serious cases and protect health care workers in the first phase. In the second phase, it focuses on reducing contagion and generating herd immunity.

A vacinação foi ativada no mundo como principal medida de contenção da pandemia causada pelo COVID-19. Para a Colômbia, foram estabelecidas cinco etapas e duas fases nas quais priorizou-se a aplicação de biológicos de acordo com as faixas etárias e perfis de risco. Segundo dados oficiais do Ministério da Saúde, durante a primeira etapa, iniciada em 17 de fevereiro de 2021, 1.453.432 pessoas foram imunizadas; na segunda, 6.620.274; na terceira, 9.325.861; na quarta, 8.436.318 e na quinta etapa, em 15 de julho, já havia 15.750.703 pessoas vacinadas Estima-se que até 21 de dezembro de 2022 esteja concluída a fase 1 da vacinação, que diz respeito às doses de reforço da população acima de cinquenta anos, enquanto se tenha cumprido quatro meses desde a aplicação da segunda dose, até então avançar para a fase 2.O Plano Nacional de Vacinação contra a COVID-19, numa primeira fase, procurou reduzir a mortalidade e a incidência de casos graves devido a este vírus, bem como proteger os trabalhadores de saúde. Na segunda fase, concentra-se em reduzir o contágio e gerar imunidade de rebanho.

Perfil del lactante con insuficiencia respiratoria que se beneficia del uso de cánula nasal de alto flujo, Bogotá - Colombia / Profile of the infant with respiratory failure benefited from the high flow nasal cannula, Bogota ­ Colombia

OBJETIVO: el propósito de este estudio fue determinar los principales desenlaces clínicos en lactantes con insuficiencia respiratoria aguda (IRA), tratados con cánula nasal de alto flujo (CNAF) en una unidad de cuidado intensivo pediátrico (UCIP). MATERIALES Y MÉTODOS: se realizó un estudio observacional descriptivo de cohorte histórica, se reclutaron niños entre 1 y 24 meses que ingresaron a la UCIP de un hospital de referencia con diagnóstico de IRA (Julio 1, 2016 a junio 30, 2017) tratados con CNAF como terapia inicial. Los datos extraídos incluyeron variables demográficas, clínicas y principales desenlaces. RESULTADOS: se identificaron 112 casos que cumplieron los criterios de inclusión durante el periodo del estudio. El diagnóstico más frecuente fue neumonía multilobar (41%), seguido por bronquiolitis (34%). Se encontró que el 22.4% de los niños poseía alguna comorbilidad, siendo la más frecuente la displasia broncopulmonar. El virus más frecuentemente aislado fue el virus sincitial respiratorio (VSR) en el 37.5% de los casos. De los 112 pacientes, 59 niños (53%) requirieron intubación traqueal. Los factores asociados con el riesgo de intubación fueron el diagnóstico de neumonía multilobar, el uso de sedación, el aislamiento de VSR y el sexo femenino. CONCLUSIONES: la CNAF es un sistema de soporte respiratorio no invasivo, seguro, bien tolerado y capaz de disminuir la necesidad de intubación y los días de estancia en cuidado intensivo. En niños con IRA, el diagnóstico de neumonía multilobar, la necesidad de sedación, la presencia de comorbilidades asociadas y el sexo femenino son factores asociados con la necesidad de requerir ventilación mecánica invasiva.

OBJECTIVE: the purpose of this study was to determine the main clinical outcomes in infants with acute respiratory failure (ARF), treated with a high-flow nasal cannula (CNAF) in a pediatric intensive care unit (PICU). MATERIALS AND METHODS: a retrospective observational study was conducted on a cohort of children between 1 and 24 months of age who were admitted to the PICU entered UCIP of a referral hospital with a diagnosis of ARF treated with CNAF as initial therapy. The data extracted included demographic and clinical variables and main outcomes. RESULTS: 112 cases were identified that met the inclusion criteria during the study period. The most frequent diagnosis was pneumonia (41%), followed by bronchiolitis (34%). It was found that 22.4% of the children had some comorbidity, the most frequent being bronchopulmonary dysplasia. The most frequently isolated virus was respiratory syncytial virus (RSV) in 37.5% of the cases. Of the 112 patients, 59 children (53%) required tracheal intubation. The factors associated with the risk of intubation were the diagnosis of pneumonia, the use of sedation, the isolation of RSV and the female gender. CONCLUSIONS: CNAF is a non-invasive respiratory support system, capable of reducing the need for intubation and days of stay in intensive care. In children with ARF, the diagnosis of pneumonia, the need for sedation, the presence of associated comorbidities, and the female gender are factors associated with the need to require invasive mechanical ventilation.

Clinical characteristics of older patients with COVID-19: a systematic review of case reports / Características clínicas de pacientes idosos com covid-19: uma revisão sistemática de relatos de casos

ABSTRACT. In the context of the current COVID-19 pandemic, higher morbidity and mortality have been reported in older adults. This age group presents physiological changes and its own clinical conditions such as frailty, dementia, among others. Objective: To describe the characteristics of COVID-19 patients, both over and under 80 years old, by conducting a systematic review of the literature describing case reports, and to summarize and critically assess these characteristics. Methods: Systematic review. The study was registered on the Registry of Health Research Projects (PRISA) of the Peruvian National Institute of Health (code EI00000631). Five electronic databases (Scopus, PubMed, PubMed Central, LILACS, and SCIELO) were systematically searched during the period between December 31, 2019 and April 16, 2020. The search focused on case reports, case studies, and case series of older people with COVID-19 infection aged over or under 80 years. When selecting the cases, priority was given to clinical and epidemiological profile, laboratory and imaging patterns, and comprehensive geriatric evaluation. Results: 1,149 articles were identified; after applying the filters, a total of 15 publications of case reports and complete records of 27 older adults were obtained. The most frequent age group was between 60 to 69 years old. There is little literature regarding case reports of older adults aged over 80 years. The most frequent parameters were hypertension, fever, cough, respiratory distress, ground-glass opacification in chest radiography and tomography. Furthermore, decrease in PaO2/FiO2 ratio and lymphocytes, and increase in C-reactive protein and Interleukin 6 were observed. Conclusions: This systematic review found little available information of patients under 80 years old, and far less for those over 80 years old, and an absence of comprehensive geriatric assessment.

RESUMO. No contexto da atual pandemia de covid-19, maior morbidade e mortalidade têm sido relatadas em idosos. Sabe-se que essa faixa etária apresenta alterações fisiológicas e condições clínicas próprias, como fragilidade, demência, entre outras. Objetivo: Descrever as características de pacientes com covid-19, maiores e menores de 80 anos, por meio de uma revisão sistemática da literatura que descreve relatos de casos, e resumir e avaliar criticamente essas características. Método: Revisão sistemática. O estudo foi registrado no Registro de Projetos de Pesquisa em Saúde (PRISA) do Instituto Nacional de Saúde do Peru (código EI00000631). Local: cinco bases de dados eletrônicas (Scopus, PubMed, PubMed Central, LILACS e SCIELO) foram sistematicamente pesquisadas entre 31 de dezembro de 2019 e 16 de abril de 2020. A busca se concentrou em relatos de caso, estudos de caso e séries de casos mais antigos pessoas com infecção por SARS-CoV-2 com mais e menos de 80 anos. Na seleção dos casos, a prioridade foi dada ao perfil clínico e epidemiológico, padrões laboratoriais e de imagem, e avaliação geriátrica abrangente. Resultados: Foram identificados 1.149 artigos. Após a aplicação dos filtros, obteve-se um total de 15 publicações de relatos de caso e registros completos de 27 idosos. A faixa etária mais frequente foi de 60 a 69 anos. Há pouca literatura sobre relatos de casos de adultos com mais de 80 anos. Os parâmetros mais frequentes foram hipertensão, febre, tosse, dificuldade respiratória, vidro fosco na radiografia e tomografia de tórax. Também foram observados diminuição da PaO2 / FiO2 e linfócitos, e aumento da proteína C reativa e Interleucina 6. Conclusões: Esta revisão sistemática encontrou poucas informações disponíveis sobre pacientes com menos de 80 anos, em quantidade ainda menor para aqueles com mais de 80 anos, além de uma ausência de avaliação geriátrica abrangente.

Double and zero quantum filtered (2)H NMR analysis of D2O in intervertebral disc tissue.

The analysis of double and zero quantum filtered (2)H NMR spectra obtained from D2O perfused in the nucleus pulposus of human intervertebral disc tissue samples is reported. Fitting the spectra with a three-site model allows for residual quadrupolar couplings and T2 relaxation times to be measured. The analysis reveals changes in both the couplings and relaxation times as the tissue begins to show signs of degradation. The full analysis demonstrates that information about tissue hydration, water collagen interactions, and sample heterogeneity can be obtained and used to better understand the biochemical differences between healthy and degraded tissue.

Controlling the effects of pulse transients and RF inhomogeneity in phase-modulated multiple-pulse sequences for homonuclear decoupling in solid-state proton NMR.

The effects of pulse imperfections and RF inhomogeneity on NMR spectra obtained with phase-modulated multiple-pulse NMR sequences are analyzed. The emphasis is on the combined effects of frequency offset, RF inhomogeneity, and pulse phase transients. To enable a theoretical description of the transients associated with phase changes under continuous RF irradiation, the nature of the transients is investigated in depth. As monitored in our 300 MHz spectrometer, they are found to be caused by linear elements of the RF circuitry. The validity of their representation as delta-function pulses and the significance of their decomposition into antisymmetric and symmetric components are discussed. A practical method for quantitative control of the antisymmetric phase transients is proposed. The linearity property allows the development of a theoretical description of the spin dynamics caused by the transients. This leads to a vector-Hamiltonian model for phase-modulated Lee-Goldburg experiments. It quantitatively predicts both the frequency shift and the line broadening caused by antisymmetric phase transients and their coupling with RF inhomogeneity. The model is shown to be equally applicable to frequency-switched Lee-Goldburg experiments. A noteworthy discovery is that for a given magnitude of the antisymmetric phase transients a frequency offset exists at which the inhomogeneity broadening is essentially canceled. This explains the common observation that for best resolution one side of resonance is preferred over the other. It also suggests a strategy for enhancing resolution without having to resort to severe sample volume restriction. Numerical calculations verified the theoretical predictions and allowed extension of the model to BLEW-12 and DUMBO-1. Experimental verification is presented. The deviations from theoretical predictions are discussed.

Internuclear distance determination of S = 1, I = 1/2 spin pairs using REAPDOR NMR.

A universal function is proposed to describe REAPDOR dephasing curves of an observed spin-1/2 nucleus dipole-recoupled to a spin-1 quadrupolar nucleus ((2)H or (14)N). Previous work had shown that, in contrast to REDOR, the shape of the dephasing curve depends on a large number of parameters including the quadrupolar coupling constant and asymmetry parameter, the sample rotation speed, the RF amplitude, and the relative orientations of the quadrupole tensor and the internuclear vector. Here we demonstrate by numerical simulations that the actual dispersion of REAPDOR dephasing curves is quite small, provided the rotation speed and the RF amplitude applied to the quadrupolar nucleus satisfy an adiabaticity condition. The condition is easily met for (2)H and is also practically achievable for virtually any (14)N-containing compound. This allows the REAPDOR curves to be approximated by a simple universal gaussian-type function, comparison of which with experimental data yields internuclear distances with less than 4% error. The spin dynamics of the recoupling mechanism is discussed. The critical importance of a stable spinning speed for optimizing the signal-to-noise ratio of the (13)C echoes is demonstrated and practical suggestions for achieving high stability are presented. Examples of applications of the universal curve are given for (2)H/(13)C and (14)N/(13)C REAPDOR in alanine.