Temporal diabetes-induced biochemical changes in distinctive layers of mouse retina.

To discover the mechanisms underlying the progression of diabetic retinopathy (DR), a more comprehensive understanding of the biomolecular processes in individual retinal cells subjected to hyperglycemia is required. Despite extensive studies, the changes in the biochemistry of retinal layers during the development of DR are not well known. In this study, we aimed to determine a more detailed understanding of the natural history of DR in Akita/+ (type 1 diabetes model) male mice with different duration of diabetes. Employing label-free spatially resolved Fourier transform infrared (FT-IR) chemical imaging engaged with multivariate analysis enabled us to identify temporal-dependent reproducible biomarkers of the individual retinal layers from mice with 6 weeks,12 weeks, 6 months, and 10 months of age. We report, for the first time, the nature of the biochemical alterations over time in the biochemistry of distinctive retinal layers namely photoreceptor retinal layer (PRL), inner nuclear layer (INL), and plexiform layers (OPL, IPL). Moreover, we present the molecular factors associated with the changes in the protein structure and cellular lipids of retinal layers induced by different duration of diabetes. Our paradigm provides a new conceptual framework for a better understanding of the temporal cellular changes underlying the progression of DR.

2DCOS and PCMW2D analysis of FT-IR/ATR spectra measured at variable temperatures on-line to a polyurethane polymerization.

In the present communication the potential of 2DCOS analysis and the spin-off technique perturbation-correlation moving window 2D (PCMW2D) analysis is illustrated with reference to spectroscopic changes observed in a data set recorded by in-line fiber-coupled FT-IR spectroscopy in the attenuated total reflection (ATR) mode during a polyurethane solution polymerization at different temperatures. In view of the chemical functionalities involved, hydrogen bonding plays an important role in this polymerization reaction. Based on the 2DCOS and PCMW2D analysis, the sequence of hydrogen bonding changes accompanying the progress of polymerization and precipitation of solid polymer can be determined. Complementary to the kinetic data derived from the original variable-temperature spectra in a previous publication the results provide a more detailed picture of the investigated solution polymerization.

Comparative Variable Temperature Studies of Polyamide II with a Benchtop Fourier Transform and a Miniature Handheld Near-Infrared Spectrometer Using 2D-COS and PCMW-2D Analysis.

The main objective of this communication is to compare the performance of a miniaturized handheld near-infrared (NIR) spectrometer with a benchtop Fourier transform near-infrared (FT-NIR) spectrometer. Generally, NIR spectroscopy is an extremely powerful analytical tool to study hydrogen-bonding changes of amide functionalities in solid and liquid materials and therefore variable temperature NIR measurements of polyamide II (PAII) have been selected as a case study. The information content of the measurement data has been further enhanced by exploiting the potential of two-dimensional correlation spectroscopy (2D-COS) and the perturbation correlation moving window two-dimensional (PCMW2D) evaluation technique. The data provide valuable insights not only into the changes of the hydrogen-bonding structure and the recrystallization of the hydrocarbon segments of the investigated PAII but also in their sequential order. Furthermore, it has been demonstrated that the 2D-COS and PCMW2D results derived from the spectra measured with the miniaturized NIR instrument are equivalent to the information extracted from the data obtained with the high-performance FT-NIR instrument.

Variable-temperature Fourier transform near-infrared imaging spectroscopy of the deuterium/hydrogen exchange in liquid D2O.

In the present publication, the deuterium/hydrogen (D/H) exchange of liquid D2O exposed to water vapor of the surrounding atmosphere has been studied by variable-temperature Fourier transform near-infrared (FT-NIR) imaging spectroscopy. Apart from the visualization of the exchange process in the time-resolved FT-NIR images, kinetic parameters and the activation energy for this D/H exchange reaction have been derived from the Arrhenius plot of the variable-temperature spectroscopic data.

3D spectral imaging with synchrotron Fourier transform infrared spectro-microtomography.

We report Fourier transform infrared spectro-microtomography, a nondestructive three-dimensional imaging approach that reveals the distribution of distinctive chemical compositions throughout an intact biological or materials sample. The method combines mid-infrared absorption contrast with computed tomographic data acquisition and reconstruction to enhance chemical and morphological localization by determining a complete infrared spectrum for every voxel (millions of spectra determined per sample).

Toward optimal spatial and spectral quality in widefield infrared spectromicroscopy of IR labelled single cells.

Advancements in widefield infrared spectromicroscopy have recently been demonstrated following the commissioning of IRENI (InfraRed ENvironmental Imaging), a Fourier Transform infrared (FTIR) chemical imaging beamline at the Synchrotron Radiation Center. The present study demonstrates the effects of magnification, spatial oversampling, spectral pre-processing and deconvolution, focusing on the intracellular detection and distribution of an exogenous metal tris-carbonyl derivative 1 in a single MDA-MB-231 breast cancer cell. We demonstrate here that spatial oversampling for synchrotron-based infrared imaging is critical to obtain accurate diffraction-limited images at all wavelengths simultaneously. Resolution criteria and results from raw and deconvoluted images for two Schwarzschild objectives (36×, NA 0.5 and 74×, NA 0.65) are compared to each other and to prior reports for raster-scanned, confocal microscopes. The resolution of the imaging data can be improved by deconvolving the instrumental broadening that is determined with the measured PSFs, which is implemented with GPU programming architecture for fast hyperspectral processing. High definition, rapidly acquired, FTIR chemical images of respective spectral signatures of the cell 1 and shows that 1 is localized next to the phosphate- and Amide-rich regions, in agreement with previous infrared and luminescence studies. The infrared image contrast, localization and definition are improved after applying proven spectral pre-processing (principal component analysis based noise reduction and RMie scattering correction algorithms) to individual pixel spectra in the hyperspectral cube.

Detection of an estrogen derivative in two breast cancer cell lines using a single core multimodal probe for imaging (SCoMPI) imaged by a panel of luminescent and vibrational techniques.

3-Methoxy-17α-ethynylestradiol or mestranol is a prodrug for ethynylestradiol and the estrogen component of some oral contraceptive formulations. We demonstrate here that a single core multimodal probe for imaging - SCoMPI - can be efficiently grafted onto mestranol allowing its tracking in two breast cancer cell lines, MDA-MB-231 and MCF-7 fixed cells. Correlative imaging studies based on luminescence (synchrotron UV spectromicroscopy, wide field and confocal fluorescence microscopies) and vibrational (AFMIR, synchrotron FTIR spectromicroscopy, synchrotron-based multiple beam FTIR imaging, confocal Raman microspectroscopy) spectroscopies were consistent with one another and showed a Golgi apparatus distribution of the SCoMPI-mestranol conjugate in both cell lines.

Synchrotron FTIR reveals lipid around and within amyloid plaques in transgenic mice and Alzheimer's disease brain.

While the basis of neuronal degeneration in Alzheimer's disease (AD) continues to be debated, the amyloid cascade hypothesis remains central. Amyloid plaques are a required pathological marker for post mortem diagnosis, and Aß peptide is regarded by most as a critical trigger at the very least. We present spectrochemical image analysis of brain tissue sections obtained with the mid-infrared beamline IRENI (InfraRed ENvironmental Imaging, Synchrotron Radiation Center, U Wisconsin-Madison), where the pixel resolution of 0.54 × 0.54 µm(2) permits analysis at sub-cellular dimensions. Spectrochemical images of dense core plaque found in hippocampus and cortex sections of two transgenic mouse models of AD (TgCRND8 and 3×Tg) are compared with plaque images from a 91 year old apoE43 human AD case. Spectral analysis was done in conjunction with histochemical stains of serial sections. A lipid membrane-like spectral signature surrounded and infiltrated the dense core plaques in all cases. Remarkable compositional similarities in early stage plaques suggest similar routes to plaque formation, regardless of genetic predisposition or mammalian origin.

Temperature-dependent Fourier transform infrared spectroscopy and Raman mapping spectroscopy of phase-separation in a poly(3-hydroxybutyrate)-poly(L-lactic acid) blend.

Variable-temperature Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopic mapping measurements were applied to study the phase separation of a poly(3-hydroxybutyrate) (PHB)-poly(L-lactic acid) (PLA) (50 : 50 wt.%) polymer-blend film as a function of temperature between 25 and 175 °C. Because of the better band separation compared with the fundamental absorptions, the first overtones of the ν(C=O) bands of PHB and PLA were used to evaluate the temperature-dependent FT-IR images as PLA-PHB and PHB-PLA band-ratio contour plots, respectively. From the visualization of the band-ratio FT-IR images, it could be derived that even beyond the melting point of PLA (145 °C), the lateral position and the geometry of the PHB-rich and PLA-rich phases were retained up to 165 °C. Furthermore, the FT-IR images derived during and after the melting of PHB (174 °C) provided an interesting insight into the homogenization process of the polymer melt. By exploiting its higher lateral resolution, valuable additional information became available from the Raman mapping measurements. Based on the Raman data, the scenario of phase-separated PHB-rich and PLA-rich domains of about 50 µm size, based on the FT-IR imaging measurements, had to be revised. Instead, the originally interpreted PHB-rich and PLA-rich domains are actually clusters of much smaller grains. Additionally, the Raman images measured in the same temperature interval revealed that the clusters of small PHB-rich grain structures aggregated as a function of temperature increase. These investigations prove that FT-IR and Raman imaging in combination with variable-temperature measurements can provide new (and so far unavailable) insights into structural phenomena of phase-separated polymer blends.

Water uptake of poly(2-N-alkyl-2-oxazoline)s: temperature-dependent Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation analysis (2DCOS).

A library of poly(2-oxazoline)s with varying length of the alkyl side-chain has been investigated by variable-temperature Fourier transform infrared (FT-IR) spectroscopy. These polymers are suitable for studies of structure-property relationships as their cationic ring-opening polymerization and the relatively facile monomer synthesis enable a control of the molecular structure. In this contribution, the number of carbon atoms in the linear side-chain is systematically varied from a short methyl to a long nonyl group. Previous studies showed that the sample library can be split in two groups: poly(2-oxazoline)s with a short side-chain (methyl-, ethyl-, and isopropyl-) exhibit hygroscopic behavior, while those with longer side-groups (butyl- and longer) were found to be semi-crystalline. To gain further insight into the mechanisms of hydrogen bonding and crystallization, temperature-dependent infrared (IR) spectroscopy has been applied in the current study. The processes involved have been monitored by generalized two-dimensional correlation spectroscopy (2DCOS) and perturbation-correlation moving-window two-dimensional correlation spectroscopy (PCMW2D) in the C=O stretching region around 1645 cm(-1). These advanced analysis techniques provided valuable additional information on the material behavior during heating. As water is removed from the samples in the course of the heating process, it was possible to clearly distinguish between "loosely associated" and hydrogen-bonded water. Furthermore, the melting process of the semi-crystalline samples could be depicted. For the poly(2-isopropyl-2-oxazoline) even a crystallization process could be monitored in the temperature range between glass transition and melting.

Variable-temperature Fourier transform near-infrared (FT-NIR) Imaging spectroscopy of the diffusion process of butanol(OD) into polyamide 11.

Time-resolved Fourier transform near-infrared (FT-NIR) spectroscopic imaging was applied to the diffusion process of butanol(OD) into polyamide 11 (PA11) with a novel sheet-structured variable-temperature-controlled sample holder in order to demonstrate the significant differences of diffusion rate below and above the glass transition temperature of PA11. The diffusant butanol(OD) was chosen for two reasons: (1) it allows the diffusion front to be monitored by the intensity decrease of a NH-specific absorption band of PA11 due to the NH/ND isotope exchange and (2) under the measurement conditions the diffusion of butanol(OD) into PA11 takes place in an experimentally manageable time frame. Apart from the in situ visualization of the diffusion front in the time-resolved FT-NIR images, the type of diffusion and the diffusion coefficient of butanol(OD) into PA11 have been determined.

Solvent interactions in methanol/N, N-dimethylamide binary systems studied by Fourier transform infrared-attenuated total reflection (FT-IR/ATR) and two-dimensional correlation spectroscopy (2D-COS).

The interaction of N,N-dimethyl formamide (DMF) and N,N-dimethyl acetamide (DMA) with methanol in solution mixtures was studied using Fourier transform infrared-attenuated total reflection (FT-IR/ATR) spectroscopy. The concentration-dependent FT-IR/ATR spectra of DMF/methanol and DMA/methanol mixtures were recorded in the wavenumber range 4000-650 cm(-1) to investigate wavenumber shifts as a consequence of hydrogen bonding interactions. In combination with two-dimensional correlation spectroscopy (2D-COS), the positional fluctuations observed in the ν(C=O) and ν(O-H) regions of DMF/DMA and methanol, respectively, have been discussed in terms of changing populations of differently hydrogen-bonded and interacting species of the same and different component molecules.

Molecular weight dependence of the thermal degradation of poly(epsilon-caprolactone): a thermogravimetric differential thermal Fourier transform infrared spectroscopy study.

The effect of molecular weight on the thermal degradation of poly(epsilon-caprolactone) (PCL) was investigated by thermogravimetric analysis in combination with differential thermal analysis and Fourier transform infrared spectroscopy (TGA/DTA/FT-IR). The measurements were made in the temperature range 40-720 degrees C and it was found that PCL undergoes completely different degradation processes in nitrogen and oxygen atmosphere. Thus, in nitrogen atmosphere low molecular weight (M(n) = 10,000 g/mol) PCL (PCL(10k)) decomposed in a three-step mechanism. The evolved gases detected by FT-IR spectroscopy were identified as epsilon-caprolactone, 5-hexenoic acid, CO(2), and methyl pentanoate and traces of H(2)O. In the case of high molecular weight (M(n) = 80,000 g/mol) PCL (PCL(80k)) only a two-step degradation was observed. By FT-IR spectroscopy 5-hexenoic acid, CO(2), H(2)O, and methyl pentanoate were detected as decomposition products. In an oxygen environment, similar degradation products were detected for the different molecular-weight PCLs. The recorded FT-IR spectra of the evolved gases were identified as CO(2), CO, H(2)O, and short-chain carboxylic acids.

In situ orientation studies of a poly(3-hydroxybutyrate)/poly(epsilon-caprolactone) blend by rheo-optical fourier transform infrared spectroscopy and two-dimensional correlation spectroscopic analysis.

In the present study, the orientation of a poly(3-hydroxybutyrate) (PHB)/poly(epsilon-caprolactone) (PCL) blend was monitored during uniaxial elongation by rheo-optical Fourier transform infrared (FT-IR) spectroscopy and analyzed by generalized two-dimensional correlation spectroscopy (2D-COS). The dichroism of the delta(CH(2)) absorption bands of PHB and PCL was employed to determine the polymer chain orientation in the PHB/PCL blend during the elongation up to 267% strain. From the PHB and PCL specific orientation functions it was derived that the PCL chains orient into the drawing direction while the PHB chains orient predominantly perpendicular to the applied strain. To extract more detailed information about the polymer orientation during uniaxial elongation, 2D-COS analysis was employed for the dichroic difference of the polarization spectra recorded during the drawing process. In the corresponding synchronous and asynchronous 2D correlation plots, absorption bands characteristic of the crystalline and amorphous regions of PHB and PCL were separated. Furthermore, the 2D-COS analysis revealed that during the mechanical treatment the PCL domains orient before the PHB domains.

Variable-temperature Fourier transform infrared spectroscopic investigations of poly(3-hydroxyalkanoates) and perturbation-correlation moving-window two-dimensional correlation analysis. Part I: Study of non-annealed and annealed poly(3-hydroxybutyrate) homopolymer.

Generalized two-dimensional correlation spectroscopy (2DCOS) and perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy were applied to explore the melting behavior of non-annealed and annealed poly(3-hydroxybutyrate) (PHB) homopolymer as studied by variable-temperature Fourier transform infrared (FT-IR) spectroscopy. The absorption band of the C=O stretching vibration was employed to investigate the structural changes during the heating process (30-200 degrees C). Non-annealed PHB showed a recrystallization process in the temperature range 30-120 degrees C. In the asynchronous 2D correlation spectrum we clearly captured the existence of two components in the crystallinity-sensitive wing of the C=O stretching mode: a well-ordered crystalline state at lower wavenumbers (1718 cm(-1)) and a less ordered crystalline state at higher wavenumbers (1724 cm(-1)). These crystallinity-sensitive bands at 1718 and 1724 cm(-1), which are not readily detectable in the one-dimensional (1D) FT-IR spectra, share asynchronous cross-peaks with bands at around 1737 and 1747 cm(-1) assignable to the C=O stretching absorptions due to the amorphous components. In the case of the melting process of non-annealed PHB in the temperature range 120-200 degrees C, it is helpful to use the PCMW2D correlation analysis, which indicates the recrystallization between 40 and 110 degrees C by the shift of the C=O stretching band from 1726 cm(-1) to 1722 cm(-1) and the sharp change to the broad amorphous C=O stretching absorption at 1747 cm(-1) at the melting temperature of PHB around 190 degrees C. For an annealed sample of PHB only the melting behavior was observed in the PCMW2D correlation analysis by the sharp transition from the crystalline to the amorphous C=O stretching band.

Variable-temperature Fourier transform infrared spectroscopic investigations of poly(3-hydroxyalkanoates) and perturbation-correlation moving-window two-dimensional correlation analysis. Part II: Study of poly(epsilon-caprolactone) homopolymer and a poly(3-hydroxybutyrate)-poly(epsilon-caprolactone) blend.

In the present study, variable-temperature Fourier transform infrared (FT-IR) spectra of a poly(epsilon-caprolactone) (PCL) homopolymer and a poly(3-hydroxybutyrate) (PHB)-poly(epsilon-caprolactone) (PCL) blend were analyzed by generalized two-dimensional correlation spectroscopy (2DCOS) and perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy. The C=O stretching vibration bands of PCL and PHB were employed to explore the structural changes in the PCL homopolymer and the PHB-PCL blend during the heating process. For the melting of PCL homopolymer in the temperature range of 50 to 70 degrees C, we observed in the synchronous and asynchronous 2D correlation spectra one crystalline (1724 cm(-1)) and one amorphous (1737 cm(-1)) C=O stretching vibration band, which are also detectable in the one-dimensional FT-IR spectra. This result was also confirmed by PCMW2D correlation spectroscopy. During the heating process of the PHB-PCL blend in the temperature range 30-200 degrees C, the PCMW2D correlation analysis provided detailed information. Thus, in the synchronous PCMW2D correlation spectrum the melting of PCL was observed in the temperature region between 30 and 70 degrees C. The recrystallization of PHB in the blend in the temperature range 70-120 degrees C was accompanied by a shift of the C=O stretching band from higher wavenumber (1724 cm(-1)) corresponding to an imperfect crystalline state to the lower wavenumber (1721 cm(-1)) characteristic of a well-ordered crystalline state. In the temperature range 120-200 degrees C the melting process of PHB in the blend is captured by a sharp transition from the crystalline (1722 cm(-1)) to the amorphous (1747 cm(-1)) C=O stretching band.

Continuous sleep EEG monitoring in PD patients with and without sleep attacks.

The pathogenesis of sleep attacks in Parkinson's disease (PD) is still unresolved. We investigated seven matched pairs of PD patients with and without a history of sleep attacks using continuous sleep EEG recording. According to the event marker altogether 12 sleep attacks were identified in three patients with a history of sleep attacks. All sleep attacks were characterized by NREM stage 1 and 2 sleep, whereas no sleep onset REM episodes were recorded. Five sleep attacks fulfilled our criteria for microsleep episodes lasting less than 120 s. The cumulative duration of microsleep episodes during the day was 27.7+/-20 min in patients with a history of sleep attacks vs. 6.4+/-4.1 min in patients without a history of sleep attacks (p=0.03), i.e., the majority of microsleep episodes were not perceived by the patients. In summary, our study suggests that sleep attacks are intrusions of NREM stage 1 and 2 sleep into wakefulness and can be identical to microsleep episodes. Future studies should systematically address the awareness of short sleep episodes in patients with PD and other disorders with increased daytime sleepiness.

[An evidence based program to support HIV-infected patients suffering from fatigue]. / Ein auf Evidenz basierendes Praxisprogramm zur pflegerischen Betreuung HIV-infizierter Menschen mit Fatigue.

Currently 15,000 to 16,000 people with HIV/AIDS are living in Switzerland. Many of these patients suffer from diverse signs and symptoms. One of the most common symptoms reported in the literature is fatigue with a rate ranging from 20 to 74%. It is well known that fatigue impacts negatively on people's activities of daily living, on their sense of physical and mental health as well as on their quality of life. Likewise many patients of the ambulatory HIV centre at the University Hospital Basel in Switzerland, report severe exhaustion and signs that indicated fatigue. In order to provide evidence-based care to these patients, a clinical practice program was developed basing on a comprehensive literature review. The program has been implemented and assists nurses to effectively assess and provide an intervention to those patients with HIV/AIDS who suffer from fatigue. The program includes the elements: screening, systematic assessment and intervention. For the systematic assessment, the Global Fatigue Index and a visual analogue scale are utilized. In this article, relevant literature has been reviewed for the development of an evidence-based program of care for patients living with HIV. Such an approach is perceived to positively affect the outcomes of patients living with HIV.

The Advanced Nursing Practice Team as a model for HIV/AIDS caregiving in Switzerland.

To offer advanced nursing care for people living with HIV, a participatory action research project was initiated that enabled constant learning and change at the levels of (a) the culture and organization of an outpatient department, (b) clinical leadership and interdisciplinary collaboration, and (c) development of new services. In this project, the development of the Advanced Nursing Practice (ANP) Team not only affected the practice of individual nurses with advanced degrees but also created a team of nurses educated at different levels. Through a systematic process, the nurses on the team became more educated and refined their clinical expertise. An essential aspect of the ANP Team was the specialization of each nurse in a self-selected topic within HIV/AIDS care. As members of the ANP Team, the nurses offer state-of-the-art nursing care including patient assessment, medication management and adherence support, symptom management, health maintenance and prevention, and family support for persons living with HIV.