Sepsis nosocomial en el recién nacido menor de 1500 gramos. Análisis epidemiológico en dos períodos de tiempo

Durante las últimas décadas se ha producido un aumento de la supervivencia de los recién nacidos pretérmino gracias a las mejoras en los tratamientos que estos pacientes reciben, entre los que se incluye el tratamiento con surfactante pulmonar, mejoras en los aparatos de ventilación mecánica, utilización de nutrición parenteral e inicio precoz de la nutrición enteral. Parte de este tratamiento incluye la prevención y detección y manejo de las infecciones de los recién nacidos menores de 1500 g (RNMBP), entre los que la sepsis de inicio tardío tiene una alta incidencia, mayor cuanto menor es el peso o la edad gestacional del recién nacido. Material y métodos. Ventajas y sesgos del estudio. Se analizaron con el programa SPSS 15.0 las características perinatales, factores de riesgo y morbimortalidad asociada a la prematuridad en relación con la aparición de un primer episodio de sepsis de inicio tardío en 222 pacientes ingresados en el Hospital Clínico San Carlos (HCSC) en los años 2007, 2008, 2011 y 2012. Se realizó un análisis univariado de cada una de las variables estudiadas en relación con la variable principal del estudio (primer episodio de sepsis con confirmación microbiológica de inicio tardío) y posteriormente se ajustaron por edad gestacional y se compararon con los datos disponibles de los hospitales miembros del grupo SEN1500 de la Sociedad Española de Neonatología y con la literatura científica disponible. Para evitar el sesgo de mala clasificación se recogieron los datos según las variables consensuadas y estandarizadas del protocolo aprobado por el grupo SEN1500 y, en aquellos casos en los que éste no hubiese descrito, se recurrió a las definiciones recogidas por otras sociedades científicas. Objetivos y resultados. Se valoraron los principales antecedentes maternales de los pacientes. En el análisis univariado solo se encontró asociación estadísticamente significativa entre parto vaginal y desarrollo de sepsis de inicio tardío, asociación que desapareció al ajustar por edad gestacional los datos. No se encontró asociación con el resto de variables de la historia materna (etnia, uso de antibioterapia preparto, uso de corticoides antenatales, embarazo múltiple o fecundación in vitro)..

Lattice-Dynamical Calculation of Second-Order Thermal Diffuse Scattering in Molecular Crystals

A computer procedure has been developed to calculate second-order thermal diffuse scattering (TDS) intensity for molecular crystals from latticedynamical calculations with an atom-atom potential in the Born-von K~irmfin formalism. It is applied to monoclinic phenothiazine and different contributions to second-order TDS intensity, acoustic-acoustic, acoustic-optic and optic-optic, are compared. Calculations are also performed in the long-wave approximation allowing for dispersion (LWD) and correction factors of Bragg intensities due to TDS contribution in the LWD approximation are, generally but not always, lower than lattice-dynamical ones; the ratio between LWD and 'exact' factors ranges from 0.4 to 1.4 for reflections considered

Structure of 1,3-Dihydro-4-[(2R)-2,5-dihydro-2-furyl]-3-phenyl-l-(p-tolyl)-2H-imidazole- 2-thione, C20HlsN2OS

Mr=334.4, orthorhombic, P212~2 ~, a= 9.366(4), b=20.616(5), c=9.137(4)A, V= 1764 (1) A 3, Z = 4, D x = 1.26 Mg m -3, 2(Mo Ka) = 0.7107 A, g = 0.18 mm -~, F(000) = 704, T= 300 K, final R--0.056 (wR =0.052) for 1979 observed reflections [I > 2a(/)]. The furanose ring is approximately planar because of the double bond, 1.289 (9) A, which affects the conformation of the ring. The dihedral angle between the furanose and imidazole least-squares planes is 69.9 (2) °. A possible C--H...O hydrogen bond has been detected involving C and O atoms in the furanose ring, giving infinite helical chains along [001 ]

First- and Second-Order Thermal Diffuse Scattering (TDS) Intensity in Molecular Crystals: Influence on Crystal Structure Parameters

First- and second-order thermal diffuse scattering (TDS) intensities are calculated in the long-wave approximation allowing for dispersion (LWD) in monoclinic phenothiazine from polarization vectors and lattice-mode frequencies obtained from lattice dynamical calculations within the harmonic approximation and the external Born-von K~irmfin formalism using an atom-atom potential function in the form V(r) =-A/r6+ B exp (-Cr). The influence of firstand second-order TDS intensity on electronic density maps is analysed and compared. Least-squares refinements of positional and thermal parameters are carried out in different ranges of sin 0/A taking into account both first- and second-order TDS contributions and the results are discussed

Structure of 4-(~-D-Erythrofuranosyl)-3-methyl- l-(p-tolyl)-4-imidazoline-2-thione Monohydrate, C 15H18N203S.H20

Mr=324.4, orthorhombic, P212t2 ~, a= 32.150(5), b=10.215(1), c=4.805(1)A, V= 1578.0 (4)/~3, Z = 4, D x = 1.36 Mg m -a, 2(Cu Ka) = 1.5418A, #=1.953mm -1, T=300K, final R= 0.050 for 1361 observed [I>2tr(I)] independent reflexions. The sugar ring adopts a conformation intermediate between envelope 2E and twist 2T forms. The orientation of the imidazoline ring with respect to the furanose is anti; the glycosidic angle is 24.6 (7) °. The crystal packing is due to hydrogen bonds involving the hydration water molecules

Lattice Dynamical Calculation of First-Order Thermal Diffuse Scattering in Phenothiazine

A computer program has been developed to calculate first-order thermal diffuse scattering (TDS) intensity from eigenvectors and eigenvalues of the dynamical matrix obtained within the harmonic approximation with an atom-atom potential function and the external Born-yon Kfirmfin formalism. It is applied to monoclinic phenothiazine and correction factors of Bragg intensities due to TDS contribution are calculated and compared with the long-wave approximation. A Fourier difference synthesis is performed in order to reveal the influence of TDS contributions in electron density maps. A least-squares process is carried out to obtain the changes in structural parameters due to TDS contribution

Lattice Dynamics and Thermal Crystallographic Parameters in Phenothiazine

A computer program has been developed to study the lattice dynamics of molecular crystals in the harmonic approximation with the external Born-yon KS.rm~n formalism and an atom-atom potential function. Dispersion curves are obtained for monoclinic phenothiazine together with frequency distribution functions and external mode contribution to thermodynamic functions. Lattice dynamical T, L and S rigid-body tensors are obtained and individual thermal tensors are compared with experiment. The disagreement with respect to experimental results is of the same order as the disagreement with a Schomaker-Trueblood fit of experimental data

Structure of l-(p-Ethoxyphenyl)-1,3-dihydro-3-phenyl-2H-benzimidazole-2-thione, C2IHlaN2OS

Mr=346-4, orthorhombic, P212121, a= 7.600(1), b= 11.132(2), c=20.767 (3)A, v= 1756.9(5)A 3, z=4, Dx=1.31Mgm -3, 2(CuKct) =.1.5418/k, /~= 1.67mm -1, F(000)=728, T= 300 K. Final R = 0.049 for 1531 observed independent reflections. The benzimid~zole bicycle is quasi-planar, the dihedral angle between the two fused rings being 1.6 (2) °. The unsubstituted phenyl ring is planar while the phenyl ring with the ethoxy substituent deviates significantly from the expected planar conformation

Structure and Absolute Configuration of 4-(a-D-Erythrofuranosyl)-1,3-dihydro-3-methyll-( p-tolyl)-2H-imidazole-2-thione, C 15 H18N2038

M r = 306.4, monoclinic, P21, a = 14.686 (6), b=5.359(4), c=9.439(3) A, fl=98.68(3) ° , V= 734.4 (7)/I,3, Z = 2, D x = 1.38 Mg m -3, 2(Mo Kct) = 0.7107 A, /t = 0-22 mm -1, F(000) = 324, T= 300 K, final R=0.042 (wR=0.037) for 1987 observed independent reflections. The sugar ring has a conformation intermediate between 3T 2 and 3E. The configuration of the imidazole ring with respect to the furanose ring is anti, the glycosidic angle being -9.3 (4) ° . The crystal packing is governed by hydrogen bonds involving OH groups and S atoms, forming infinite chains along [001]

Incommensurate instability and lattice dynamics of potassium selenate within a semiempirical rigid-ion model

The lattice dynamics of potassium selenate is analyzed using a rigid-ion model with the selenate groups reduced to rigid bodies. The interatomic forces have been adjusted only using static structural data. The number of adjustable parameters varies from two to five. Such a simple model is already sufficient to reproduce semiquantitatively the phonon dynamics of the real system. In particular, the model exhibits the lattice instability leading to the existence of an incommensurate phase. The characteristics of the resulting soft mode agree with those observed experimentally. The calculated eigenvector, in excellent agreement with the experimental one, is rather insensitive to the details of the interactions. This explains the strong similarities of the incommensurate modulations in most A2BX4 compounds. On the other hand, the form of the soft-phonon branch strongly depends on the force model. It is sufficient to fit the model to the static structure observed at 145 K instead of the one at room temperature, to provoke a conspicuous softening of the branch. The branch minimum is specially sensitive to some potassium-oxygen interactions. The relative size of the cations plays an essential role in the origin of the incommensurate instability. For comparison the results of a similar analysis for Cs2SeO4 are presented. In this case, the unstable or soft character of the lowest 2 branch disappears.Dirección General de Investigación Científica y Técnica PB87-074