Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 65
Filter
1.
Rev. chil. infectol ; Rev. chil. infectol;38(5): 720-723, oct. 2021. tab
Article in Spanish | LILACS | ID: biblio-1388291

ABSTRACT

INTRODUCCIÓN: En las últimas décadas, se ha incrementado la prevalencia de infecciones por bacilos gramnegativos resistentes a carbapenémicos. OBJETIVO: Determinar los tipos y la frecuencia de las distintas carbapenemasas en aislados de Klebsiella spp. y Pseudomonas aeruginosa, en seis hospitales de alta complejidad de Bogotá-Colombia. MÉTODOS: Estudio observacional descriptivo en seis hospitales de la ciudad de Bogotá, en el período de enero de 2017 a agosto de 2018. Se realizaron RPC para genes de KPC, GES, VIM, NDM, IMP y OXA-48 en cepas de Klebsiella spp y P aeruginosa resistentes a carbapenémicos. RESULTADOS: 52 aislados de P aeruginosa amplificaron para una carbapenemasa, de los cuales 39 (75%) fueron positivos para KPC, 11 (21%) para VIM y 2 co-producciones de KPC y VIM. En cuanto a Klebsiella spp., 165 cepas amplificaron al menos para una carbapenemasa, 98% expresaron KPC y 4 aislados tuvieron co-producciones de metalo-beta-lactamasas y KPC. DISCUSIÓN: Este estudio aporta información valiosa, como el incremento de producción de KPC en P. aeruginosa y la co-producción de KPC y metalo-beta-lactamasas, locual tiene una implicancia tanto en la selección del tratamiento, las medidas de aislamiento de contacto y el pronóstico de los pacientes.


BACKGROUND: In the last decades, the prevalence of infections by carbapenem resistant gram-negative bacilli has been increased. OBJECTIVE: To determine types and frequency of the different carbapenemases in Klebsiella spp. and Pseudomonas aeruginosa, in six hospitals in Bogotá-Colombia. METHODS: Descriptive and observational study, in six hospitals in the city of Bogotá, in the period ftom January 2017 to August 2018. PCR were performed for KPC, GES, VIM, NDM, IMP and OXA-48 genes, in carbapenem resistant Klebsiella spp. and P aeruginosa. RESULTS: 52 P aeruginosa isolates amplified a carbapenemase gene, of which 39 (75%) were positive for KPC, 11 (21%) for VIM and two co-productions of KPC and VIM. Regarding Klebsiella spp. 165 strains amplified at least one carbapenemase gene, 98% expressed KPC and four isolates had co-productions of metallo-P-lactamases and KPC. DISCUSSION: This study provides valuable information, such as the increased production of KPC in P. aeruginosa información valiosa, como el incremento de producción de KPC en P. aeruginosa and the co-production of KPC plus metallobetalactamases, which has an implication both in treatment selection, isolation precautions and patient prognosisy.


Subject(s)
Humans , Pseudomonas aeruginosa/genetics , Klebsiella , Bacterial Proteins/genetics , beta-Lactamases/genetics , Microbial Sensitivity Tests , Carbapenems/pharmacology , Colombia/epidemiology , Hospitals , Anti-Bacterial Agents/pharmacology
2.
Chemphyschem ; 22(19): 1939-1946, 2021 10 05.
Article in English | MEDLINE | ID: mdl-34291548

ABSTRACT

The antiphase character of the PHIP associated signals after a hydrogenation reaction is particularly sensitive to line broadening introduced by magnetic field inhomogeneities and interferences by the presence of resonance lines steaming from a large amount of thermally polarized spins. These obstacles impose a limitation in the detection of reaction products as well as in the experimental setups. A simple way to overcome these impediments consists of acquiring the signal with a train of refocusing pulses instead of a single r.f. pulse. We present here a number of examples where this multipulse acquisition, denominated PhD-PHIP, displays its potentiality in improving the information related to hyperpolarized spins performed in a sample, where the former parahydrogen nuclei are part of a complex J-coupling network.

3.
J Magn Reson ; 323: 106894, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33387958

ABSTRACT

A new pulse sequence aimed to filter out NMR signals coming from thermally polarized protons in PHIP experiments based on the OPSY pulse sequence (Only Parahydrogen SpectroscopY) is presented. In analogy to OPSY, which removes thermal polarization by using a pair of magnetic field gradient pulses with an intensity ratio 1:2 and equal duration, the same effect can be achieved using inhomogeneous radiofrequency fields. The spatial dependence of the radiofrequency field is used to control the Hamiltonian, which results in an effective suppression of thermal contributions in the NMR signal, while PHIP originated signals remain unmodified. A theoretical model for the radiofrequency encoded only parahydrogen (REOPSY) sequence is presented along with an experimental implementation on a birdcage coil in a 7 T magnetic field. The control level achieved by this strategy allows the inclusion of a long train of refocusing pulses. Therefore, the new sequence can be combined with the parahydrogen discriminated PHIP (PhD-PHIP) pulse sequence as a detection block to improve sensitivity and resolution in a single-scan experiment. Experiments with REOPSY and REOPSY+PhD-PHIP are presented in thermally and hyperpolarized samples.

4.
Rev Chilena Infectol ; 38(5): 720-723, 2021 10.
Article in Spanish | MEDLINE | ID: mdl-35506842

ABSTRACT

BACKGROUND: In the last decades, the prevalence of infections by carbapenem resistant gram-negative bacilli has been increased. OBJECTIVE: To determine types and frequency of the different carbapenemases in Klebsiella spp. and Pseudomonas aeruginosa, in six hospitals in Bogotá-Colombia. METHODS: Descriptive and observational study, in six hospitals in the city of Bogotá, in the period ftom January 2017 to August 2018. PCR were performed for KPC, GES, VIM, NDM, IMP and OXA-48 genes, in carbapenem resistant Klebsiella spp. and P aeruginosa. RESULTS: 52 P aeruginosa isolates amplified a carbapenemase gene, of which 39 (75%) were positive for KPC, 11 (21%) for VIM and two co-productions of KPC and VIM. Regarding Klebsiella spp. 165 strains amplified at least one carbapenemase gene, 98% expressed KPC and four isolates had co-productions of metallo-P-lactamases and KPC. DISCUSSION: This study provides valuable information, such as the increased production of KPC in P. aeruginosa información valiosa, como el incremento de producción de KPC en P. aeruginosa and the co-production of KPC plus metallobetalactamases, which has an implication both in treatment selection, isolation precautions and patient prognosisy.


Subject(s)
Klebsiella , Pseudomonas aeruginosa , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Carbapenems/pharmacology , Colombia/epidemiology , Hospitals , Humans , Microbial Sensitivity Tests , Pseudomonas aeruginosa/genetics , beta-Lactamases/genetics
5.
J Magn Reson ; 320: 106833, 2020 Nov.
Article in English | MEDLINE | ID: mdl-33032245

ABSTRACT

DOSY is a powerful spectroscopic NMR technique that resolves components in mixtures through the evaluation of different diffusion coefficients. The application of DOSY to dilute mixtures is hampered by the low signal to noise ratios (SNR), leading to long acquisition times. The use of PHIP may resolve this issue as long as reproducible signals are obtained in order to perform 2D experiments. Here we show that the use of hollow membranes and adequate gas flow produce constant polarization for a time-span that enables the acquisition of 2D experiments. A pressure gradient is evidenced by the presence of convection, which is accounted for by using a DPGSE sequence. The influence of J-coupling evolution during the sequence is studied both numerically and experimentally, to determine the optimum echo-time. The applicability of the method for samples with poor SNR is explored by setting the reaction rate to achieve a low intensity of polarized signals.

6.
J Magn Reson ; 299: 28-32, 2019 Feb.
Article in English | MEDLINE | ID: mdl-30554041

ABSTRACT

Despite the large degree of polarization in PHIP experiments compared to the Boltzmann factor, the presence of a large amount of non-reacted molecules with thermal polarization is an important obstacle when dealing with very diluted samples. The feasibility of enhancing both sensitivity and resolution in a single experiment by combining two well established pulse sequences, OPSY and PHD-PHIP is presented. OPSY is used as a block for filtering the signals originated from thermally polarized protons. PhD-PHIP, on the other hand, is used as an acquisition block, increasing the resolution and further improving the sensitivity by preventing signal canceling in the presence of magnetic field inhomogeneities. Experiments in a complex sample with very low hyperpolarization levels are presented showing the excellent performance of the method.

8.
J Magn Reson ; 289: 55-62, 2018 Apr.
Article in English | MEDLINE | ID: mdl-29471276

ABSTRACT

We demonstrate that the relative phases in the refocusing pulses of multipulse sequences can compensate for pulse errors and off-resonant effects, which are commonly encountered in J-spectroscopy when CPMG is used for acquisition. The use of supercycles has been considered many times in the past, but always from the view point of time-domain NMR, that is, in an effort to lengthen the decay of the magnetization. Here we use simple spin-coupled systems, in which the quantum evolution of the system can be simulated and contrasted to experimental results. In order to explore fine details, we resort to partial J-spectroscopy, that is, to the acquisition of J-spectra of a defined multiplet, which is acquired with a suitable digital filter. We unambiguously show that when finite radiofrequency pulses are considered, the off-resonance effects on nearby multiplets affects the dynamics of the spins within the spectral window under acquisition. Moreover, the most robust phase cycling scheme for our setup consists of a 4-pulse cycle, with phases yyyy‾ or xxxx‾ for an excitation pulse with phase x. We show simulated and experimental results in both thermally polarized and PHIP hyperpolarized systems.

9.
Neotrop Entomol ; 47(2): 256-270, 2018 Apr.
Article in English | MEDLINE | ID: mdl-28905263

ABSTRACT

The genus Oliveiriella (Chironomidae, Orthocladiinae) was erected by Wiedenbrug & Fittkau (1997). The adults have characteristic black spots on their wings and other characteristics similar to the genus Cricotopus. Pupal skins are very characteristic with strong short spines in the anal lobe instead of setae, while larvae are distinguishable by the long anal papillae and the intense blue color of their body. However, Andersen et al (2013) consider Oliveiriella as a subgenera of Cricotopus. In this paper, using the sequences of the cox1 gene, we conclude that Oliveiriella should be considered a subgenus within Cricotopus, confirming its status in Andersen et al (2013). Furthermore, we describe Cricotopus (Oliveiriella) rieradevallae Prat & Paggi sp. n. from the Saltana river (Ecuador). The adult males, females, and preimaginal stages of the two species of subgenus Oliveiriella known from South America Cricotopus (O.) almeidai n. comb. from Peru, Brazil, and Argentina and Cricotopus (O.) sanjavieri n. comb. from Argentina are compared with those of Cricotopus (O.) rieradevallae sp. n. from Ecuador. The differences allow the distinction of the three species. The cox1 gene reveals that at least three different undescribed species of the same subgenus are present in the high-altitude tropical Andes. The morphology of the available pupae and pupal exuviae reveals the presence of several morphotypes that are candidates to be described as new species. A key used to distinguish these pupal morphotypes is provided, including the three described species. Additionally, the distribution of the subgenus is discussed.


Subject(s)
Altitude , Chironomidae/anatomy & histology , Chironomidae/classification , Phylogeny , Rivers , Animals , Female , Larva , Male , Pupa , South America , Wings, Animal
10.
Chemosphere ; 149: 168-76, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26855221

ABSTRACT

Tyre pyrolysis char (TPC), produced when manufacturing pyrolysis oil from waste tyre, was used as raw material to prepare activated carbons (ACs) by KOH activation. KOH to TPC weight ratios (W) between 0.5 and 6, and activation temperatures from 600 to 800 °C, were used. An increase in W resulted in a more efficient development of surface area, microporosity and mesoporosity. Thus, ACs derived from TPC (TPC-ACs) with specific surface areas up to 814 m(2) g(-1) were obtained. TPC, TPC-ACs and a commercial AC (CAC) were tested for removing Tetracycline (TC) in aqueous phase, and systematic adsorption studies, including equilibrium, kinetics and thermodynamic aspects, were performed. Kinetics was well described by the pseudo-first order model for TPC, and by a pseudo second-order kinetic model for ACs. TC adsorption equilibrium data were also fitted by different isotherm models: Langmuir, Freundlich, Sips, Dubinin-Radushkevich, Dubinin-Astokov, Temkin, Redlich-Peterson, Radke-Prausnitz and Toth. The thermodynamic study confirmed that TC adsorption onto TPC-ACs is a spontaneous process. TC adsorption data obtained in the present study were compared with those reported in the literature, and differences were explained in terms of textural properties and surface functionalities. TPC-ACs had similar performances to those of commercial ACs, and might significantly improve the economic balance of the production of pyrolysis oil from waste tyres.


Subject(s)
Charcoal/chemistry , Hydroxides/chemistry , Potassium Compounds/chemistry , Tetracycline/analysis , Water Pollutants, Chemical/analysis , Adsorption , Carbon , Kinetics , Temperature , Tetracycline/chemistry , Water Pollutants, Chemical/chemistry
11.
Food Chem ; 192: 950-7, 2016 Feb 01.
Article in English | MEDLINE | ID: mdl-26304434

ABSTRACT

The effect of fiber addition on the distribution and mobility of protons in biscuits is studied by using low resolution time domain nuclear magnetic resonance (TD-NMR). The proportion of flour is reduced in order to incorporate inulin and oat fiber. NMR temperature dependent experiments are carried out in order to gain insight on the processes occurring in biscuit baking. Proton populations were identified measuring spin-spin relaxation times (T2). The major change in the relaxation profiles upon incorporation of fibers corresponds to mobile water molecules, which appear to be related to dough spreading behavior and biscuit quality. Biscuit samples baked in a commercial oven were studied by two dimensional spin-lattice/spin-spin (T1-T2) relaxation maps. The T1/T2 ratio is used as an indicator of the population mobility, where changes in the mobility of water in contact with flour components as starch, proteins and pentosans are observed.


Subject(s)
Dietary Fiber/analysis , Flour/analysis , Magnetic Resonance Spectroscopy/methods , Protons , Avena/chemistry , Dietary Proteins/chemistry , Food Technology , Inulin/chemistry , Starch/chemistry , Water/chemistry
12.
J Magn Reson ; 251: 1-7, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25554943

ABSTRACT

Parahydrogen induced polarization (PHIP) is a powerful hyperpolarization technique. However, as the signal created has an anti-phase characteristic, it is subject to signal cancellation when the experiment is carried out in inhomogeneous magnetic fields or in low fields that lack the necessary spectral resolution. The use of benchtop spectrometers and time domain (TD) analyzers has continuously grown in the last years and many applications are found in the food industry, for non-invasive compound detection or as a test bench for new contrast agents among others. In this type of NMR devices the combination of low and inhomogeneous magnetic fields renders the application of PHIP quite challenging. We have recently shown that the acquisition of J-spectra in high magnetic fields not only removes the anti-phase peak cancellation but also produces a separation of thermal from hyperpolarized signals, providing Parahydrogen Discriminated (PhD-PHIP) spectra. In this work we extend the use of PhD-PHIP to low and inhomogeneous fields. In this case the strong coupling found for the protons of the sample renders spin-echo spectra that have a great complexity, however, a central region in the spectrum with only hyperpolarized signal is clearly identified. This experimental approach is ideal for monitoring real time chemical reaction of pure PHIP signals.

13.
J Magn Reson ; 230: 155-9, 2013 May.
Article in English | MEDLINE | ID: mdl-23500529

ABSTRACT

The application of parahydrogen for the generation of hyperpolarization has increased continuously during the last years. When the chemical reaction is carried out at the same field as the NMR experiment (PASADENA protocol) an antiphase signal is obtained, with a separation of the resonance lines of a few Hz. This imposes a stringent limit to the homogeneity of the magnetic field in order to avoid signal cancellation. In this work we detect the signal arising from hyperpolarized Hexene by means of a CPMG pulse train. After Fourier transformation the obtained J-spectra not only presents an enhanced spectral resolution but also avoids partial peak cancellation.


Subject(s)
Algorithms , Hydrogen/analysis , Hydrogen/chemistry , Magnetic Resonance Spectroscopy/methods , Materials Testing/methods , Models, Chemical , Computer Simulation , Isomerism
14.
Neotrop Entomol ; 42(6): 607-17, 2013 Dec.
Article in English | MEDLINE | ID: mdl-27193279

ABSTRACT

The distribution of the genus Barbadocladius Cranston & Krosch (Diptera: Chironomidae), previously reported from Chile to Bolivia, has extended northwards. Larvae, pupae and pupal exuviae of this genus have been found in the high mountain tropical streams of Peru to 9°22'56″, but are restricted to very high altitude streams (altitudes over 3,278 m asl) compared to the lower altitude streams (below 1,100 m asl) in which the genus is reported in Chile and Argentina. Based on morphological studies, both described species in the genus, Barbadocladius andinus Cranston & Krosch and Barbadocladius limay Cranston & Krosch, have been found in Peru as pupae or pupal exuviae. Morphological analysis of the larvae and pupae revealed no differences between the two described species from Patagonia and Peru, which are of similar size and with a similar armament of hooklets and spines in pupal tergites and sternites. However, molecular analysis of larvae and pupae revealed that in Peru, there are at least two different evolutionary lines, one distributed widely and another restricted to one site. Phylogenetic analysis (using cox1 mitochondrial sequences) of all available sequences of Barbadocladius shows that the Chilean and Argentinean material differs from that of Peru. Therefore, a total of four molecular segregates are identified, although morphologically, neither larvae nor the pupae may be differentiated.


Subject(s)
Chironomidae/genetics , Genetics, Population , Phylogeny , Altitude , Animal Distribution , Animals , Argentina , Bolivia , Chile , Rivers
15.
Rev. Fac. Nac. Salud Pública ; 30(3): 265-272, sep.-dic. 2012. ilus, tab
Article in Spanish | LILACS | ID: lil-669239

ABSTRACT

La mortalidad materno-infantil refleja el grado de desarrollo social y económico de un país, por lo que la salud reproductiva es una prioridad sanitaria; su prevención depende directamente de la cobertura y calidad de los servicios de salud. OBJETIVOS: evaluar el apego de la atención prenatal a la NOM 007 y su correlación con la morbilidad materna en una unidad de salud de San Luis Potosí, México. METODOLOGIA:estudio descriptivo, correlacional y cuantitativo, cuya unidad de análisis fueron 571 expedientes de embarazadas atendidas durante el 2008. Para probar la hipótesis se utilizó r de Pearson, p = 0,05. RESULTADOS: el rango de edad osciló entre 13 y 43 años, 37,1% adolescentes; 44,3% se incorporó a la atención en el segundo trimestre del embarazo; 38,2% cumplió con mínimo cinco consultas; 46,4% presentó morbilidad, con la infección urinaria como la más común (224 casos). El apego de la atención prenatal fue adecuado en 2,6% de los casos, según las acciones efectuadas; las de promoción de salud fueron las menos realizadas. CONCLUSION: el nivel de apego de la atención prenatal a la NOM 007 se calificó inadecuado en 97,4%, coincidiendo con morbilidad materna (87,5 -100%); esto podría relacionarse con consultas más frecuentes para algunas mujeres, el ingreso tardío a la atención y la consecuente reducción del tiempo para la realización de las acciones. La correlación resultó contraria a lo esperado, pues a mayor apego de la atención prenatal a la norma, mayor morbilidad materna se presentó (r = 0,318, p < 0,000).


Mother and child mortality reflects the level of social and economic development of a country; therefore, reproductive health is a sanitary priority. Mortality prevention depends directly on the coverage and quality of health services. OBJECTIVE: to assess the compliance of prenatal care with the NOM 007 norm and its correlation with maternal morbidity in a health center located in San Luis Potosí, Mexico. METHOGOLOGY: a descriptive, correlational, and quantitative study in which the units of analysis were the medical records of 571 pregnant women cared for during 2008. In order to prove the hypothesis, Pearson’s r was used. The p value was ≤ 0.05. RESULTS: ages ranged from 13 to 43 years. Additionally, 37.1% of the patients were teenagers and 44.3% began receiving attention during the second trimester of their pregnancy; 38.2% attended at least five medical appointments, and 46.4% had morbidity. For the latter group, urinary infection was the most common condition (224 cases). Prenatal attention was adequate in 2.6% of the cases according to the actions performed. Health promotion actions were the least frequent. CONCLUSION: the level of compliance with the NOM 007 norm for prenatal care was considered inadequate in 97.4% of the cases and was consistent with maternal morbidity (87.5-100%). This could be related to more frequent appointments for some women and with late treatment, which resulted in less time to perform said actions. Contrary to expectations, greater compliance meant higher maternal morbidity (r = 0.318, p < 0.000).


Subject(s)
Humans , Female , Pregnancy , Adolescent , Adult , Prenatal Care , Morbidity , Health Promotion , Maternal Mortality , Total Quality Management , Health Services Accessibility
16.
J Invertebr Pathol ; 109(1): 169-71, 2012 Jan.
Article in English | MEDLINE | ID: mdl-22146240

ABSTRACT

A PCR-based method was developed for the detection and identification of two species of grasshopper-specific pathogens belonging to the genus Entomophaga in North America, Entomophaga calopteni and Entomophaga macleodii. Two separate sets of primers specific for amplification of a DNA product from each species of Entomophaga as well as a positive control were utilized. Grasshoppers were collected from two sites in Mexico during an epizootic with grasshoppers found in "summit disease", typical of Entomophaga infections. There was a preponderance of Melanopline grasshoppers infected by E. calopteni. The described method is an accurate tool for identification of North American grasshopper infections by Entomophaga species.


Subject(s)
Entomophthorales/isolation & purification , Grasshoppers/microbiology , Zygomycosis/microbiology , Animals , DNA, Fungal/genetics , Entomophthorales/genetics , Entomophthorales/pathogenicity , Mexico/epidemiology , Polymerase Chain Reaction , Spores, Fungal/genetics , Zygomycosis/diagnosis , Zygomycosis/epidemiology
17.
Solid State Nucl Magn Reson ; 36(2): 77-85, 2009 Oct.
Article in English | MEDLINE | ID: mdl-19589661

ABSTRACT

Two proton quasi-equilibrium states were previously observed in nematic liquid crystals, namely the S and W quasi-invariants. Even though the experimental evidence suggested that they originate in a partition of the spin dipolar energy into a strong and a weak part, respectively, from a theoretical viewpoint, the existence of an appropriate energy scale which allows such energy separation remains to be confirmed and a representation of the quasi-invariants is still to be given. We compare the dipolar NMR signals yielded both by the Jeener-Broekaert (JB) experiment as a function of the preparation time and the free evolution of the double quantum coherence (DQC) spectra excited from the S state, with numerical calculations carried out from first principles under different models for the dipolar quasi-invariants, in a 10-spin cluster which represents the 5CB (4(')-pentyl-4-biphenyl-carbonitrile) molecule. The calculated signals qualitatively agree with the experiments and the DQC spectra as a function of the single-quantum detection time are sensible enough to the different models to allow both to probe the physical nature of the initial dipolar-ordered state and to assign a subset of dipolar interactions to each constant of motion, which are compatible with the experiments. As a criterion for selecting a suitable quasi-equilibrium model of the 5CB molecule, we impose on the time evolution operator consistency with the occurrence of two dipolar quasi-invariants, that is, the calculated spectra must be unaffected by truncation of non-secular terms of the weaker dipolar energy. We find that defining the S quasi-invariant as the subset of the dipolar interactions of each proton with its two nearest neighbours yields a realistic characterization of the dipolar constants of motion in 5CB. We conclude that the proton-spin system of the 5CB molecule admits a partition of the dipolar energy into a bilinear strong and a multiple-spin weak contributions therefore providing two orthogonal constants of motion, which can be prepared and observed by means of the JB experiment. This feature, which implies the existence of two timescales of very different nature in the proton-spin dynamics, is ultimately dictated by the topology of the spin distribution in the dipole network and can be expected in other liquid crystals. Knowledge of the nature of the dipolar quasi-invariants will be useful in studies of dipolar-order relaxation, decoherence and multiple quantum NMR experiments where the initial state is a dipolar-ordered one.

18.
J Chem Phys ; 130(2): 024501, 2009 Jan 14.
Article in English | MEDLINE | ID: mdl-19154032

ABSTRACT

Previous work showed that by means of the Jeener-Broekaert (JB) experiment, two quasiequilibrium states can be selectively prepared in the proton spin system of thermotropic nematic liquid crystals (LCs) in a strong magnetic field. The similarity of the experimental results obtained in a variety of LC in a broad Larmor frequency range, with crystal hydrates, supports the assumption that also in LC the two spin reservoirs, into which the Zeeman order is transferred, originate in the dipolar energy and that they are associated with a separation in energy scales: A constant of motion related to the stronger dipolar interactions (S), and a second one (W) corresponding to the secular part of the weaker dipolar interactions with regard to the Zeeman and the strong dipolar part. We study the nature of these quasi-invariants in nematic 5CB (4(')-pentyl-4-biphenyl-carbonitrile) and measure their relaxation times by encoding the multiple-quantum coherences of the states following the JB pulse pair on two orthogonal bases, Z and X. The experiments were also performed in powder adamantane at 301 K which is used as a reference compound having only one dipolar quasi-invariant. We show that the evolution of the quantum states during the buildup of the quasiequilibrium state in 5CB prepared under the S condition is similar to the case of powder adamantane and that their quasiequilibrium density operators have the same tensor structure. In contrast, the second constant of motion, whose explicit operator form is not known, involves a richer composition of multiple-quantum coherences of even order on the X basis, in consistency with the truncation inherent in its definition. We exploited the exclusive presence of coherences of +/-4,+/-6,+/-8, besides 0 and +/-2 under the W condition to measure the spin-lattice relaxation time T(W) accurately, so avoiding experimental difficulties that usually impair dipolar order relaxation measurement such as Zeeman contamination at high fields and also superposition of the different quasi-invariants. This procedure opens the possibility of measuring the spin-lattice relaxation of a quasi-invariant independent of the Zeeman and S reservoirs, so incorporating a new relaxation parameter useful for studying the complex molecular dynamics in mesophases. In fact, we report the first measurement of T(W) in a LC at high magnetic fields. Comparison of the obtained value with the one corresponding to a lower field (16 MHz) points out that the relaxation of the W-order strongly depends on the intensity of the external magnetic field, similarly to the case of the S reservoir, indicating that the relaxation of the W-quasi-invariant is also governed by the cooperative molecular motions.

19.
Am J Med Genet A ; 146A(4): 479-83, 2008 Feb 15.
Article in English | MEDLINE | ID: mdl-18203165

ABSTRACT

Mesomelic dysplasias (MD) are a group of skeletal disorders with exclusive or predominant shortness of the middle segment of the limbs, with or without involvement of the hands/feet or other body parts. Short stature is a usual consequence due to involvement of the lower limbs. In 2003, Camera and Camera reported an unusual upper limb MD with normal stature and radiological evidence of long bone metaphyseal dysplasia. Here, we describe a Mexican patient showing a similar clinical and radiological phenotype, in addition to esophageal atresia, palpebral ptosis and slight lower limb asymmetry. This represents the second case reported in the literature, corroborating the existence of this rare entity.


Subject(s)
Body Height , Osteochondrodysplasias/complications , Upper Extremity Deformities, Congenital/complications , Body Height/physiology , Child, Preschool , Humans , Male , Mexico
20.
Acta méd. peru ; 24(2): 21-25, mayo-agos. 2007. graf, tab
Article in Spanish | LILACS-Express | LILACS, LIPECS | ID: lil-692283

ABSTRACT

Introducción: Los trastornos Acido Base (TAB) son una patología Frecuente de los pacientes de las Unidades de Cuidados Intensivos (UCIs), por ello es importante evaluar la morbimortalidad de este trastorno en estas unidades. Objetivo: determinar la incidencia de los Trastornos Acido Base (TAB) y su relación con la estancia hospitalaria y mortalidad en la Unidad de Cuidados Intensivos (UCI). Material y métodos: Resultados: durante el período del estudio se hospitalizaron 131 pacientes. En 100 la edad promedio fue 66.9 ± 18, 9 años, el puntaje APACHE II promedio fue 18,07 ± 7,62 puntos, la estancia hospitalaria en UCI fue 6,42 ± 7,78 días y la mortalidad dentro de la UCI fue del 24% (24 pacientes). Los valores gasométricos fueron pH 7,39 ± 0.11, paCO2 37.79 ± 10,08 mmHg. BE- 1,40 ± 6,93 mEq/Lt y bicarbonato 23.78 ± 5,92 mEq/Lt. Los TAB más frecuentes fueron acidosis metabólica (21%) y los trastornos mixtos primariamente metabólicos (20%). No se encontró TAB en 14% de los pacientes. El TAB con mayor estancia hospitalaria en UCI fue la acidosis respiratoria (9,14 ± 6,1 días) y los trastornos mixtos primariamente respiratorios (9,75 ± 8,0 días). El mayor porcentaje de mortalidad se observó en los grupos con acidosis metabólica (28,6%) y acidosis respiratoria (27%). Conclusiones: la incidencia de los TAB fue alta (86%). Los trastornos metabólicos (acidosis y mixto) fueron los de mayor incidencia; los trastornos respiratorios (acidosis y mixto) estuvieron asociados a mayor estancia en UCI y la acidosis (metabólica y respiratoria) estuvieron asociadas a mayor mortalidad.


Introducction: Acid-Base(A - B) alterations are a frequent problem of patients in Intensive Care Units (ICUs); therefore, it’s important to evaluate morbidity and mortality of this pathology in the ICUs Objetive: to determine the incidence of Acid Base (A-B) disorders and their relationship with lenght of hospitalization and mortality in the Intensive Care Unit (ICU). Material and methods: Results: during the period of the study of 131 pacients were hospitalized. In 100 the mean age was 66.9 ± 18,9 years, the mean APACHE II score was 18,07 7,62 points; the mean hospital stay in ICU was 6,42 ± 7,78 days and the mortality within the ICU was 24% (24 patients). The gasometric mean values were pH 7,39 ± 0.11, paCO2 37.79 ± 10,08 mmHg. BE- 1,40 ± 6,93 mEQ/Lt. The more frequent A-B disorders were metabolic acidosis (21%) and mixed primary metabolic alterations (20%). No A-B disorder was found in 14% of the patients. The A-B disorders with longer hospital stays in ICU were respiratory acidosis (9,14 6,1 days) and mixed primary metabolic alterations (9,75 ± 8,0 days). Greater mortality was observed in the groups with metabolic acidosis (28,6%) and respiratory acidosis (27%). Conclusions: the incidence of A-B disorders was high (86%). Metabolic alterations (acidosis and mixed) had a greater incidence; the respiratory alterations (acidosisand mixed) were associated with longer ICU stays and the acidoses (metabolic and respiratory) were associated with greater mortality.

SELECTION OF CITATIONS
SEARCH DETAIL