Microscopic examination of intracellular organisms in bronchoalveolar lavage fluid for the diagnosis of ventilator-associated pneumonia：a prospective multi-center study

Background The presence of intracellular organisms （ICOs） in polymorphonuclear leukocytes obtained from bronchoalveolar lavage fluid （BALF） is a possible method for rapid diagnosis of ventilator-associated pneumonia （VAP）.However,the validity of this diagnostic method remains controversial and the diagnostic thresholds reported by investigators were different.Our objective was to evaluate the accuracy of quantification of ICOs in BALF for the diagnosis of VAP,and to detect the best cutoff percentage of PMNs containing ICOs （PIC） in the microscopic examination of BALF for the diagnosis of VAP.Methods This was a prospective multi-center study conducted in 4 ICUs in Wuhan,China,which involved 181 patients suspected of first episode of VAP.BALF was obtained from all enrolled patients.The BALF samples underwent quantitative culture,cytological and bacteriological analysis to detect the culture results,PIC values and the morphological features of microorganisms.Definite diagnosis of VAP was based on pre-set criteria.The receiver-operating characteristic curve was used to detect the best cutoff point for PIG to diagnose VAP,and the diagnostic accuracy was calculated.Moreover,quantitative culture and Gram＇s stain of BALF were adopted to diagnose VAP,and their diagnostic accuracy was evaluated as well.Results There were 102 patients definitely diagnosed with VAP （VAP group）,and 60 patients definitely diagnosed without VAP （no VAP group）.We found that ICOs were present in 96.08％ （98 out of 102） of VAP patients and 20.00％ （12 out of 60） of no VAP patients.The PICs were significantly higher （（9.53±6.65）％ vs.（0.52±1.33）％,P＜0.01） in VAP group.In our study,the best cutoff point for PIC to diagnose VAP was 1.5％,which had a sensitivity of 94.12％,a specificity of 88.33％,a positive predictive value （PPV） of 93.20％ and a negative predictive value （NPV） of 89.83％.The area under the receiveroperating characteristic curve was 0.956 （95％ confidence interval,0.925-0.986; P＜0.01）.When the positive quantitative culture results of BALF were used to diagnose VAP,the sensitivity,specificity,PPV and NPV were 65.69％,95.00％,95.71％ and 61.96％,respectively.Whereas they were 70.59％,76.67％,83.72％ and 60.53％,respectively,when the positive Gram＇s stain results of BALF were used to diagnose VAP.The concordance between the results of Gram＇s stain and quantitative cultures was poor,only 32.10％ （52 out of 162） was totally right,and 17.28％ （28 out of 162） was partially right.Conclusions PIC＞1.5％ has good diagnostic performance in the microscopic examination of BALF for the diagnosis of VAP.However,Gram＇s stain is not reliable for the early application of antibiotic therapy,due to the poor bacteriological predictive value.

Challenges and Progress in Evaluating Apple Root Resistance Responses to Pythium ultimum Infection

Due to the hidden nature of roots in the soils, it is more challenging to investigate their resistance traits and defense responses as compared to those of the aerial organs. At the same time, it is self-evident that root health is fundamental to a plant’s entire life and productivity. It is also easily conceivable that root function, physiology, morphology, and architecture are constantly impacted by the complex soil environment including both biotic and abiotic factors. This report summarizes and updates the challenges and progress in evaluating resistance responses of apple root to infection from a necrotrophic oomycete pathogen, Pythium ultimum. Several obstacles impede the progress of investigating apple root resistance traits including the difficulties of direct and real-time evaluation and the lack of a continuous supply of apple plants for repeated infection assays. Systematic and detailed analyses were made possible by implementing a micropropagation procedure for continuously generating uniform apple plants for repeated infection assays. As a result, an elite panel of apple rootstock germplasm with distinct resistance levels was identified. These apple rootstock genotypes with well-defined resistance levels are the much-needed plant materials for subsequent genomics and transgenics analyses to define the functional roles of specific candidate genes. Careful microscopic examination revealed contrasting necrosis progression patterns between resistant and susceptible genotypes, which shed light on the potential mechanisms underlying resistance traits. Our continuing research will provide a clearer view regarding the genetic elements regulating resistance traits in apple roots to P. ultimum infection.

Experimental infectivity of Theileria luwenshuni and Theileria uilenbergi in Chinese Kunming mice

Theileria luwenshuni and Theileria uilenbergi are important tick-borne pathogens and cause substantial losses to the sheep industry in China. The improvement in detection techniques has allowed the identification of multi-homing parasitism in Theileria parasites. Herein we evaluated the experimental infectivity of T. luwenshuni and T. uilenbergi in Chinese Kunming mice by screening blood samples of experimentally inoculated mice by microscopic examination（ME） and PCR. T. luwenshuni infected Chinese Kunming mice and 20 mice inoculated with this parasite were positive by ME and PCR. In addition, T. uilenbergi infected mice and 20 mice inoculated with this species were positive by ME and PCR. However, the number of red blood cells and the levels of hemoglobin of 40 infected mice had no obvious changes in the course of infection. Our results demonstrated the multi-homing parasitism of T. luwenshuni and T. uilenbergi, which were believed to be parasites of sheep and goats. This study was the first to demonstrate the infection of T. luwenshuni and T. uilenbergi in Kunming mice.

Effect of Pb Content on Phase Composition and Property of Bi-Pb-Sr-Ca-Cu-O System Superconductors

The addition of Pb in the superconductors of BiSrCaCuO system is very helpful for growth of the high-Tc phase (Tc 110K). We prepared a series of samples with nominal composition of Bi2-xPbxSr2Ca2Cu3Oy (0.1&lex&le2). The zero resistance transition temperature Tc of 106K and the critical transport current density Jc of 1 × 103A/cm2 at 77K have been obtained for the samples of Bi2-xPbxSr2Ca2Cu3Oy (x=0.2 and 0.3). The X-ray diffraction analysis and measurement of AC magnetic susceptibility confirmed that the material is comprised of single high-Tc phase. We also report the magnetic properties of this material as well as the results of TEM observation.

Study of Carbon Contaminated Epitaxial Silicon

The properties of the carbon contaminated silicon epitaxial layer and its surface have been studied by means of JAMP-10 Auger electron microprobe and JEM-2000FX transmission scanning electron microscope. The results show that the fog defects on the surface are due to carbon contamination. The existence of SiC in the silicon epitaxial layer has been identified by the electron diffraction analysis.

Growth Kinetic Studies for MOCVD CdTe and HgCdTe Epilayers on GaAs Substrates

The growth rates of CdTe and CMT on GaAs and on CdTe/GaAs substrates were studied as a function of temperature and gas composition. A Langmuir-Hinshelwood Model for surface reaction control region is suggested. The CdTe/GaAs interface was examined by X-ray double crystal diffraction, laser Raman spectroscopy and transmission electron microscopy (TEM). A defect layer was observed at CdTe/GaAs interface. The relationship between interface qualities and electrical properties of CMT overlayers was discussed.

TEM Morphology and FCP Rate of Ti-5Al-2Mo-3Zr Alloy

The transmission electron microscopic morphology of the phases and fatigue crack propagation (FCP) rate of Ti-5Al-2Mo-3Zr alloy were investigated in this study. Microstructure of the alloy consists of α and β phases after furnace- and air-cooling, and interfacial phase appears at the boundaries between these two phases. After water quenching, the microstructure consists primary of α and h.c.p. martensite α′ which assumes acicular. There are many twins within the α′ plates. No retained β phase exists after quenching from any temperature. During aging, β particles precipitated along the boundaries and inside the martensite plates with Burgers orientation relationship. The fatigue crack propagation rate (low frequency) is not sensitive to the microstructure, tensile strength and rolling direction. Analysis of the fractography shows that main cracks propagated serpentinely and secondary cracks existed everywhere. In high stress intensity range, the resistance of FCP is better than that of Ti-6Al-4V.

High J_c Y-Ba-Cu-O Superconductor Tape

In December of 1988, the authors successfully developed a high Jc Y-Ba-Cu-O superconductor tape on a nickel substrate by means of powder rolling. The tape is 0.94mm2 in cross-section and its critical current is 21.0A at 77K and in zero applied field. The microstructures of the tapes with different Jc were analysed by TEM. The result shows that the tapes with different Jc have different microstructures. From the facts, it can be concluded that making the grain boundary 'clean' might have some effects on the weak-link problem and the twin zone might act as fluxing pinning centers. Therefore, to purify the grain boundary, to thin the twin and to homogenize the microstructure will be of benefit in increasing Jc.

Models for the Formation and Dispersion of Potassium-filled Bubbles in Doped Tungsten Wire

The evolution of potassium-filled pores during the production and annealing of tungsten wire was observed by SEM and TEM, and the basic parameters of potassium-filled bubble rows were measured statistically. Based on disturbance theory and diffusion theory, analyses of shape unstability of tube-shaped second phases or pores in the metallic matrix are suitable for potassium-filled tubes in doped tungsten. Breakup models of long and thin potassium-filled tubes and ring shaped potassium-filled bubbles are given. The relationship between basic parameters of potassium-filled bubble rows and the size of potassium-filled tubes and the condition under which a potassium-filled tube can break up during annealing are also derived.

Preparation and characterization of SiO_2/TiO_2/methylcellulose hybrid thick films for optical waveguides

SiO_2/TiO_2/methylcellulose composite materials processed by the sol-gel technique were studied for optical waveguide applications. With the help of methylcellulose, an organic binder, SiO2/TiO2/methylcellulose hybrid thick films were prepared by a single spin-coating processes. After annealing at 70 °C for an hour, 2.5-μm crack-free and dense organic-inorganic hybrid optical films with a refractive index of 1.537 were achieved. Optical losses of plane waveguide made up of those films and ordinary slide glass substrate are around 0.3 dB/cm at 650 nm. Scanning electronmicroscopy (SEM) and UV-visible spectroscopy (UV-VIS), have been used to characterize the thick films.

A study on the best irradiation dose of X-ray for Hep-2 cells by Fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy （FTIR） was employed to study the human epidermis larynx carcinoma cell lines （Hep-2） which were irradiated by different doses of X-ray. The results show that （1） the irradiation of X-ray damages the structure of the CH3 groups of the thymine in DNA, which restrains the reproduction of Hep-2 cells effectively, （2） the 8 Gy dose of X-ray irradiation changes the framework and the relative contents of some proteins, lipids and the nucleic acid molecules intercellular in the greatest degree, and （3） the 8 Gy dose of X-ray irradiation is the best irradiation dose for lowering the degree of the cancerization of Hep-2 cells according to the criteria for the degree of the cancerization reported recently. Meanwhile, the apoptosis of these cells were detected by using flow cytometry （FCM） primarily. It shows that the apoptotic ratio of the Hep-2 cells depends on the irradiation dose to some extent, but is not linearly. And the apoptotic ratio of the 12 Gy dose group is the maximum （20.36%）, but the apoptotic ratios of the 2 to 8 Gy dose groups change little.