Discriminating between normal and glaucomatous eyes using the Heidelberg Retina Tomograph, GDx Nerve Fiber Analyzer, and Optical Coherence Tomograph

OBJECTIVE

To compare the ability of 3 instruments, the Heidelberg Retina Tomograph (HRT), the GDx Nerve Fiber Analyzer (GDx), and the Optical Coherence Tomograph (OCT), to discriminate between healthy eyes and eyes with early to moderate glaucomatous visual field loss.

SUBJECTS AND METHODS

Forty-one patients with early to moderate glaucomatous visual field loss and 50 healthy subjects were included in the study. The HRT, GDx, and OCT imaging and visual field testing were completed on 1 eye from each subject within a 6-month interval. Statistical differences in sensitivity at fixed specificities of 85%, 90%, and 95% were evaluated. In addition, areas under the receiver operating characteristic (ROC) curve were compared.

RESULTS

No significant differences were found between the area under the ROC curve and the best parameter from each instrument: OCT thickness at the 5-o'clock inferior temporal position (mean +/- SE, 0.87 +/- 0.04), HRT mean height contour in the nasal inferior region (mean +/- SE, 0.86 +/- 0.04), and GDx linear discriminant function (mean +/- SE, 0.84 +/- 0.04). Twelve HRT, 2 GDx, and 9 OCT parameters had an area under the ROC curve of at least 0.81. At a fixed specificity of 90%, significant differences were found between the sensitivity of OCT thickness at the 5-o'clock inferior temporal position (71%) and parameters with sensitivities less than 52%. Qualitative assessment of stereophotographs resulted in a sensitivity of 80%.

CONCLUSION

Although the area under the ROC curves was similar among the best parameters from each instrument, qualitative assessment of stereophotographs and measurements from the OCT and HRT generally had higher sensitivities than measurements from the GDx.

New Developments in Medical Applications of Hybrid Hydrogels Containing Natural Polymers

New trends in biomedical applications of the hybrid polymeric hydrogels, obtained by combining natural polymers with synthetic ones, have been reviewed. Homopolysaccharides, heteropolysaccharides, as well as polypeptides, proteins and nucleic acids, are presented from the point of view of their ability to form hydrogels with synthetic polymers, the preparation procedures for polymeric organic hybrid hydrogels, general physico-chemical properties and main biomedical applications (i.e., tissue engineering, wound dressing, drug delivery, etc.).

New antimicrobial chitosan derivatives for wound dressing applications

Chitosan is a non-toxic, biocompatible, biodegradable natural cationic polymer known for its low imunogenicity, antimicrobial, antioxidant effects and wound-healing activity. To improve its therapeutic potential, new chitosan-sulfonamide derivatives have been designed to develop new wound dressing biomaterials. The structural, morphological and physico-chemical properties of synthesized chitosan derivatives were analyzed by FT-IR, (1)H NMR spectroscopy, scanning electron microscopy, swelling ability and porosity. Antimicrobial, in vivo testing and biodegradation behavior have been also performed. The chitosan derivative membranes showed improved swelling and biodegradation rate, which are important characteristics required for the wound healing process. The antimicrobial assay evidenced that chitosan-based sulfadiazine, sulfadimethoxine and sulfamethoxazole derivatives were the most active. The MTT assay showed that some of chitosan derivatives are nontoxic. Furthermore, the in vivo study on burn wound model induced in Wistar rats demonstrated an improved healing effect and enhanced epithelialization of chitosan-sulfonamide derivatives compared to neat chitosan. The obtained results strongly recommend the use of some of the newly developed chitosan derivatives as antimicrobial wound dressing biomaterials.

Spectral characterization of eucalyptus wood

The main difficulties in wood and pulp analyses arise principally from their numerous components with different chemical structures. Therefore, the basic problem in a specific analytical procedure may be the selective separation of the main carbohydrate-derived components from lignin due to their chemical association and structural coexistence. The processing of the wood determines some structural modification in its components depending on the type of wood and the applied procedure. Fourier transform infrared (FT-IR) spectrometry and X-ray diffraction have been applied to analyze Eucalyptus g. wood chips and unbleached and chlorite-bleached pulp. The differences between samples have been established by examination of the spectra of the fractions obtained by successive extraction (acetone extractives, acetone free extractive samples, hemicelluloses, and lignins) by evaluating the derivative spectra, band deconvolution, etc. The energy and the hydrogen bonding distance have been evaluated. The relationship between spectral characteristics and sample composition has been established, as well as the variation of the degree of crystallinity after pulping and bleaching. The integral absorption and lignin/carbohydrate ratios calculated from FT-IR spectra of the IR bands assigned to different bending or stretching in lignin groups are stronger in the spectrum of eucalyptus chips than those from brown stock (BS) pulp spectra because of the smaller total amount of lignin in the latter. FT-IR spectra clearly show that after chlorite bleaching the structure of the wood components is partially modified or removed. Along with FT-IR data, the X-ray results confirmed the low content of lignin in the pulp samples by increasing the calculated values of the crystalline parameters. It was concluded that FT-IR spectroscopy can be used as a quick method to differentiate Eucalyptus globulus samples.

Polymeric Nanocomposites and Nanocoatings for Food Packaging: A Review

Special properties of the polymeric nanomaterials (nanoscale size, large surface area to mass ratio and high reactivity individualize them in food packaging materials. They can be processed in precisely engineered materials with multifunctional and bioactive activity. This review offers a general view on polymeric nanocomposites and nanocoatings including classification, preparation methods, properties and short methodology of characterization, applications, selected types of them used in food packaging field and their antimicrobial, antioxidant, biological, biocatalyst and so forth, functions.

Progresses in Food Packaging, Food Quality, and Safety-Controlled-Release Antioxidant and/or Antimicrobial Packaging

Food packaging is designed to protect foods, to provide required information about the food, and to make food handling convenient for distribution to consumers. Packaging has a crucial role in the process of food quality, safety, and shelf-life extension. Possible interactions between food and packaging are important in what is concerning food quality and safety. This review tries to offer a picture of the most important types of active packaging emphasizing the controlled/target release antimicrobial and/or antioxidant packaging including system design, different methods of polymer matrix modification, and processing. The testing methods for the appreciation of the performance of active food packaging, as well as mechanisms and kinetics implied in active compounds release, are summarized. During the last years, many fast advancements in packaging technology appeared, including intelligent or smart packaging (IOSP), (i.e., time-temperature indicators (TTIs), gas indicators, radiofrequency identification (RFID), and others). Legislation is also discussed.

Fluoroscopy-based navigation system in spine surgery

The variability in width, height, and spatial orientation of a spinal pedicle makes pedicle screw insertion a delicate operation. The aim of the current paper is to describe a computer-assisted surgical navigation system based on fluoroscopic X-ray image calibration and three-dimensional optical localizers in order to reduce radiation exposure while increasing accuracy and reliability of the surgical procedure for pedicle screw insertion. Instrumentation using transpedicular screw fixation was performed: in a first group, a conventional surgical procedure was carried out with 26 patients (138 screws); in a second group, a navigated surgical procedure (virtual fluoroscopy) was performed with 26 patients (140 screws). Evaluation of screw placement in every case was done by using plain X-rays and post-operative computer tomography scan. A 5 per cent cortex penetration (7 of 140 pedicle screws) occurred for the computer-assisted group. A 13 per cent penetration (18 of 138 pedicle screws) occurred for the non computer-assisted group. The radiation running time for each vertebra level (two screws) reached 3.5s on average in the computer-assisted group and 11.5s on average in the non computer-assisted group. The operative time for two screws on the same vertebra level reaches 10 min on average in the non computer-assisted group and 11.9 min on average in the computer-assisted group. The fluoroscopy-based (two-dimensional) navigation system for pedicle screw insertion is a safe and reliable procedure for surgery in the lower thoracic and lumbar spine.

Characterization by Fourier Transform Infrared Spectroscopy (FT-IR) and 2D IR Correlation Spectroscopy of PAMAM Dendrimer

FT-IR and 2D correlation spectroscopy were employed to study the microstructural changes occurring during phase transitions of a liquid crystal poly(amidoamine) codendrimer (PAMAM (L1)16(L2)16) generation 3, functionalized on the terminal groups by one-chain promesogenic calamitic units (4-(4'-decyloxybenzoyloxy)salicylaldehyde (L1)) and two-chain promesogenic calamitic units (4-(3',4'-didecyloxybenzoyloxy)salicylaldehyde (L2)). Spectral modifications associated with molecular conformation rearrangements allowing for molecular shape change on going from a liquid-crystalline organization to another were found. The transition temperatures were calculated, and they are in good agreement with the DSC data. Spectral analysis gives evidence of the LC phase transitions and to an additional transition associated with the existence of conformers. Various types of hydrogen bonding have been established.

Structural analysis of photodegraded lime wood by means of FT-IR and 2D IR correlation spectroscopy

In this study the weathering behavior of lime wood (Tillia cordata Mill.) has been examined using FT-IR and 2D IR correlation spectroscopy, which evidenced chemical changes induced by exposure to weathering conditions. It was showed that lignin is most sensitive component to the photodegradation processes as indicated by considerable decreases in the intensities of the characteristic aromatic lignin band at 1505cm(-1) and other associated bands. By 2D correlation spectroscopy has been demonstrated that the moment of CO from carboxyl and acetyl groups in hemicelluloses is changing first, followed by the CC of aromatic skeletal, CO in non-conjugated ketones, carboxyl groups and lactones, absorbed O-H and conjugated C-O groups in quinones. The carbonyl formation corresponded well with lignin degradation, indicating a close relationship between them. Comparing the rate of carbonyl formation and lignin decay clearly showed that the former is remarkably higher than the latter, indicating the formation of carbonyl bands at 1738cm(-1) probably resulted from not only lignin oxidation but also from reactions occurring in other components of the wood. Quinine formation is combined with the decay of aromatic structures and the formation of conjugated carbonyl groups.

Chitosan-Based Bionanocomposite Films Prepared by Emulsion Technique for Food Preservation

Biopolymer nanocomposite films were prepared by casting film-forming emulsions based on chitosan/Tween 80/rosehip seed oil and dispersed montmorillonite nanoclay C30B. The effect of composition on structural, morphological characteristics and, mechanical, barrier, antimicrobial and antioxidant properties was studied. The presence of rosehip seed oil in chitosan films led to the formation of flexible films with improved mechanical, gas and water vapour barrier properties and antioxidant activity. The in vitro antibacterial tests against Escherichia coli, Salmonella typhymurium, and Bacillus cereus showed that the chitosan/rosehip seed oil/montmorillonite nanoclay composites effectively inhibited all the three microorganisms.