Evaluation of bedside pulmonary function in the neonate: From the past to the future

Pulmonary function testing and monitoring plays an important role in the respiratory management of neonates. A noninvasive and complete bedside evaluation of the respiratory status is especially useful in critically ill neonates to assess disease severity and resolution and the response to pharmacological interventions as well as to guide mechanical respiratory support. Besides traditional tools to assess pulmonary gas exchage such as arterial or transcutaenous blood gas analysis, pulse oximetry, and capnography, additional valuable information about global lung function is provided through measurement of pulmonary mechanics and volumes. This has now been aided by commercially available computerized pulmonary function testing systems, respiratory monitors, and modern ventilators with integrated pulmonary function readouts. In an attempt to apply easy-to-use pulmonary function testing methods which do not interfere with the infant́s airflow, other tools have been developed such as respiratory inductance plethysmography, and more recently, electromagnetic and optoelectronic plethysmography, electrical impedance tomography, and electrical impedance segmentography. These alternative technologies allow not only global, but also regional and dynamic evaluations of lung ventilation. Although these methods have proven their usefulness for research applications, they are not yet broadly used in a routine clinical setting. This review will give a historical and clinical overview of different bedside methods to assess and monitor pulmonary function and evaluate the potential clinical usefulness of such methods with an outlook into future directions in neonatal respiratory diagnostics.

Carbon Nanotube Conductive Networks through the Double Percolation Concept in Polymer Systems

We investigated the electrical conductivity and percolation behavior of binary and ternary nanocomposites based on multiwalled carbon nanotubes (MWCNs) using polypropylene (PP) and a blend of PP with cyclic butylene terephthalate (CBT). The nanocomposites were prepared by diluting a commercial 20 %wtMWCNT PP masterbatch using optimized melt-mixing conditions. The concentration of carbon nanotubes in the diluted PP samples was as low as 0.5 % and as high as 15 % in weight. For the PP/CBT blend CBT concentration was varied up to 40 %wt while the loading of CNT was from 0 to 5 %wt. SEM and TEM techniques were used to examine the quality of the dispersion and the formation of nanotube networks within the polymer matrix. TEM and Raman spectroscopy results showed that for the diluted PP/MWCNT composites the nanotubes are well aligned in samples obtained the microinjection molding process, although the level of alignment is less with crystalline PP than in an amorphous matrix such as polycarbonate (PC). FTIR and XRD results revealed that the orientation of both polymer chains and crystals decreased with the incorporation of nanotubes into PP. The electrical conductivity was also significantly altered by the nanotube alignment in a PP matrix, as was previously observed for PC/MWCNT composites; the conductivity decreased and the percolation threshold rose in highly sheared samples; however, the presence of a crystalline phase improved the conductivity even for high shear conditions through the phenomenon of double percolation threshold. This last concept refers to the requirement that the filler-rich phase be continuous and conductive and not to the existence of two percolation thresholds at two different CNT concentrations. The electrical conductivity of PP/CBT blends was also improved through a double percolation that is the basic requirement for the conductivity of the ternary nanocomposites.

A new catalytic-spectrophotometric method for quantification of trace amounts of nitrite in fruit juice samples

A new kinetic method has been developed for the determination of nitrite in fruit juice samples. The method is based on the catalytic effect of nitrite with the oxidation of Nile Blue A (NBA) by KBrO(3) in the sulfuric acid medium. The optimum conditions obtained are 1.2 mM sulfuric acid, 0.034 mM of NBA, 2.8 × 10(-3) M KBrO(3), reaction temperature of 20 °C, and reaction time of 100 s at 595.5 nm. Under the optimized conditions, the method allowed the quantification of nitrite in a range of 0.2-800 μg/mL with a detection limit of 0.02 μg/mL. The method was applied to the determination of nitrite in 15 brands of fruit juice samples.

New kinetic-spectrophotometric method for monitoring the concentration of iodine in river and city water samples

A new kinetic method has been developed for the determination of iodine in water samples. The method is based on the catalytic effect of I(-) with the oxidation of Indigo Carmine (IC) by KBrO(3) in the sulfuric acid medium. The optimum conditions obtained are 0.16 M sulfuric acid, 1 × 10(-3) M of IC, 1 × 10(-2) M KBrO(3), reaction temperature of 35°C, and reaction time of 80 s at 612 nm. Under the optimized conditions, the method allowed the quantification of I(-) in a range of 12-375 ng/mL with a detection limit of 0.46 ng/mL. The method was applied to the determination of iodine in river and city water samples with the satisfactorily results.

Polyphenols attached graphene nanosheets for high efficiency NIR mediated photodestruction of cancer cells

Green tea-reduced graphene oxide (GT-rGO) sheets have been exploited for high efficiency near infrared (NIR) photothermal therapy of HT29 and SW48 colon cancer cells. The biocompatibility of GT-rGO sheets was investigated by means of MTT assays. The polyphenol constituents of GT-rGO act as effective targeting ligands for the attachment of rGO to the surface of cancer cells, as confirmed by the cell granularity test in flow cytometry assays and also by scanning electron microscopy. The photo-thermal destruction of higher metastatic cancer cells (SW48) is found to be more than 20% higher than that of the lower metastatic one (HT29). The photo-destruction efficiency factor of the GT-rGO is found to be at least two orders of magnitude higher than other carbon-based nano-materials. Such excellent cancer cell destruction efficiency provided application of a low concentration of rGO (3 mg/L) and NIR laser power density (0.25 W/cm(2)) in our photo-thermal therapy of cancer cells.

Evaluation of nutrient agar for the culture of Mycobacterium tuberculosis using the microcolony detection method

We evaluated nutrient agar using the microcolony detection method for the recovery of Mycobacterium tuberculosis on 37 acid-fast bacilli (AFB) positive sputum specimens, and compared it with conventional Löwenstein-Jensen (LJ) medium. Nutrient agar detected 35 isolates compared to 34 on LJ medium. The mean time to detection of mycobacteria on nutrient agar and LJ medium was respectively 9.6 and 21.4 days. The contamination rate on nutrient agar and LJ medium was respectively 5.4% and 2.7%. Nutrient agar detects M. tuberculosis more rapidly than LJ medium, and could be an economical, rapid culture method in resource-poor settings, provided our findings are confirmed by further studies.

Molecular characterization of pathogenic Fusarium species in cucurbit plants from Kermanshah province, Iran

Fusarium is one of the important phytopathogenic genera of microfungi causing serious losses on cucurbit plants in Kermanshah province, the largest area of cucurbits plantation in Iran. Therefore, the objectives in this study were to isolate and identify disease-causing Fusarium spp. from infected cucurbit plants, to ascertain their pathogenicity, and to determine their phylogenetic relationships. A total of 100 Fusarium isolates were obtained from diseased cucurbit plants collected from fields in different geographic regions in Kermanshah province, Iran. According to morphological characters, all isolates were identified as Fusarium oxysporum, Fusarium proliferatum, Fusarium equiseti, Fusarium semitectum and Fusarium solani. All isolates of the five Fusarium spp. were evaluated for their pathogenicity on healthy cucumber (Cucumis sativus) and honeydew melon (Cucumis melo) seedlings in the glasshouse. F. oxysporum caused damping-off in 20-35 days on both cucurbit seedlings tested. Typical stem rot symptoms were observed within 15 days after inoculation with F. solani on both seedlings. Based on the internal transcribed spacer (ITS) regions of ribosomal DNA (rDNA) restriction fragment length polymorphism (RFLP) analysis, the five Fusarium species were divided into two major groups. In particular, isolates belonging to the F. solani species complex (FSSC) were separated into two RFLP types. Grouping among Fusarium strains derived from restriction analysis was in agreement with criteria used in morphological classification. Therefore, the PCR-ITS-RFLP method provides a simple and rapid procedure for the differentiation of Fusarium strains at species level. This is the first report on identification and pathogenicity of major plant pathogenic Fusarium spp. causing root and stem rot on cucurbits in Iran.

Evaluation of the current trend of nalidixic acid susceptibility in typhoidal Salmonellae; a marker of therapeutic failure for the fluoroquinolones

BACKGROUND AND OBJECTIVES

Typhoid is a major health problem faced by the developing countries like Pakistan. More than 20 million cases are reported annually worldwide. Currently fluoroquinolones are the drugs of choice to treat typhoid fever. In vivo resistance to fluoroquinolones leading to therapeutic failure is developing rapidly and is becoming a major concern for the clinicians. The objective of this study was to determine the sensitivity pattern of Nalidixic acid over the last four years

MATERIAL AND METHODS

A descriptive cross sectional study was carried out at the Microbiology Department of the Army Medical College, National University of Sciences and Technology, Rawalpindi from January 2006 to December 2009. All the isolates were dealt with standard microbiological procedures. The antimicrobial sensitivity of Nalidixic acid and Ciprofloxacin was determined using Kirby-Bauer disc diffusion method as per the guidelines of Clinical and Laboratory Standard Institute (CLSI).

RESULTS

Out of 240 isolates, 111 were Salmonella typhi and 129 were Salmonella paratyphi A. The resistance of the typhoidal Salmonella to Nalidixic acid has reached significant levels and it seems only a matter of time when hundred percent resistance will be encountered. All isolates were sensitive to Ciprofloxacin on disc diffusion method.

CONCLUSION

Resistance to Nalidixic acid predicting therapeutic failure with fluoroquinolones is on a steady rise.

Quantification of sub-nanomolar levels of Penicillin G by differential pulse adsorptive stripping voltammetry

A novel selective and sensitive method is developed for determination of Penicillin G by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV). Penicillin G gave well-resolved diffusion-controlled cathodic peaks at -0.42 and -0.584 V, respectively (vs Ag/AgCl) in pH 7.50 of borate buffer. Optimal conditions were obtained as pH 7.50, accumulation potential of -0.2 V (vs Ag/AgCl), accumulation time of 120 s, and scan rate of 100 mV/s. Under the optimized conditions, a linear calibration curve was established for the concentration of Penicillin G in the range of 0.007-2.13 µg/ml with a detection limit of 0.000717 µg/ml. The procedure was successfully applied to the determination of Penicillin G in various medicine and biological samples. The relative standard deviation of the method at 0.05 and 0.5 µg/ml Penicillin G, for 10 runs, was 2.55% and 2.06%, respectively.

Evaluation of thin-layer agar 7H11 for the isolation of Mycobacterium tuberculosis complex

We evaluated the thin-layer agar (TLA) method for the recovery of Mycobacterium tuberculosis complex and compared the results with the BACTEC Mycobacteria Growth Indicator Tube (MGIT) 960 system. A total of 53 mycobacterial isolates were isolated on both media. The recovery rates of mycobacteria on TLA and BACTEC MGIT 960 system were respectively 90.6% and 96.2%. Mean time to detection of mycobacteria on TLA was 12.5 compared to 11.2 days on BACTEC MGIT 960. TLA is a simple technique and can be used as an alternative to the Löwenstein-Jensen medium and BACTEC MGIT 960 for the isolation of mycobacteria in resource-poor settings.

305 OPTIMIZING DONOR AND RECIPIENT FACTORS IN XENOGRAFTING OF TESTIS TISSUE

Grafting of donor mammalian testis tissue into recipient mice allows completion of spermatogenesis in the grafted tissue and therefore can serve as a new option for preservation of male germ line. For testis tissue xenografting, castrated male nude mice typically serve as recipients, each receiving 8 testis tissue fragments; however, no study has comprehensively investigated donor and recipient factors. The objective of this study was to determine the effects of strain of immunodeficient recipient mouse (nude v. SCID), gonadal status (intact v. gonadectomized), and gender (male v. female) on the outcome of testis tissue xenografting. A secondary objective was to determine the optimal number of testis tissue fragments per mouse most suitable for xenografting. Testis parenchyma from newborn piglets were cut into small fragments (5 mg each) and grafted under the back skin of different groups of immunodeficient mice. In Experiment 1, 8 groups of mice (n = 7/group) served as recipients: castrated male nude, intact male nude, ovariectomized female nude, intact female nude, castrated male SCID, intact male SCID, ovariectomized female SCID, and intact female SCID. In Experiment 2, 4 groups of mice (n = 10/group) served as recipients of 2, 4, 8, or 16 testis tissue fragments per mouse. Recipient mice were sacrificed 8 months after grafting and the weight of the grafts and vesicular glands (male mice) were compared among groups by analysis of variance. In Experiment 1, mouse gonadal status (intact v. gonadectomized) did not affect the total graft weight (P > 0.05), but both the recipient mouse strain (nude v. SCID) and gender (male v. female) affected the total graft weight (2460 ± 320.9, 1420 ± 290.0, 758 ± 156.7, and 2780 ± 297.4, mean ± SEM, P < 0.0001 for SCID, nude, female, and male mice, respectively). In Experiment 2, the total graft weight was highest in the group of mice receiving 8 testis tissue fragments (192 ± 76.1, 695 ± 96.5, 2443 ± 338.8, and 1458 ± 305.4, mean ± SEM, P < 0.0001 for 2, 4, 8, or 16 fragment groups, respectively). These results collectively indicate that male SCID mice receiving 8 testis tissue fragments provide optimized conditions for the recovery of largest grafts. Research was supported by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Saskatchewan Health Research Foundation (SHRF) to A. Honaramooz and scholarships from the Western College of Veterinary Medicine and the International Peace Scholarship to S. Abbasi.

Self-assembly from milli- to nanoscales: methods and applications

The design and fabrication techniques for microelectromechanical systems (MEMS) and nanodevices are progressing rapidly. However, due to material and process flow incompatibilities in the fabrication of sensors, actuators and electronic circuitry, a final packaging step is often necessary to integrate all components of a heterogeneous microsystem on a common substrate. Robotic pick-and-place, although accurate and reliable at larger scales, is a serial process that downscales unfavorably due to stiction problems, fragility and sheer number of components. Self-assembly, on the other hand, is parallel and can be used for device sizes ranging from millimeters to nanometers. In this review, the state-of-the-art in methods and applications for self-assembly is reviewed. Methods for assembling three-dimensional (3D) MEMS structures out of two-dimensional (2D) ones are described. The use of capillary forces for folding 2D plates into 3D structures, as well as assembling parts onto a common substrate or aggregating parts to each other into 2D or 3D structures, is discussed. Shape matching and guided assembly by magnetic forces and electric fields are also reviewed. Finally, colloidal self-assembly and DNA-based self-assembly, mainly used at the nanoscale, are surveyed, and aspects of theoretical modeling of stochastic assembly processes are discussed.