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Biomedical subjects

Thomas Berger

Publications and source records attributed to Thomas Berger.

At least 19 recordsLinked to original sources
PubMed2006

Increased serum levels of soluble CD14 indicate stable multiple sclerosis.

The aim of this study was to evaluate a possible role of soluble CD14 (sCD14) in multiple sclerosis (MS). We found that sCD14 serum levels measured by ELISA were higher in MS patients compared to neurological and healthy controls. Within the MS group sCD14 levels were increased in relapsing-remitting and secondary progressive MS compared to primary progressive MS. Furthermore, sCD14 concentrations were increased during stable disease. An increased expression of sCD14 was also detected after treatment with interferon-beta. In summary, we report evidence that serum sCD14 levels are increased in MS and correlate inversely with disease activity in relapsing MS patients.

Adult↗
PubMed2006

Low dose treatment with the synthetic cannabinoid Nabilone significantly reduces spasticity-related pain : a double-blind placebo-controlled cross-over trial.

About 30% of patients with chronic upper motor neuron syndrome (UMNS) suffer from disabling spasticity-related pain not sufficiently correctable by conventional treatment. Delta9-tetrahydrocannabinol (Delta(9)-THC) was reported to add benefit in the treatment of pain in patients with multiple sclerosis (MS). The question arose whether synthetic cannabinoids with lower potential for psychotropic side effects could be effective as well. To evaluate the safety and efficacy of low dose treatment with the synthetic cannabinoid Nabilone (1 mg per day) on spasticity-related pain a placebo-controlled double-blind crossover trial was performed.11 out of 13 included patients completed the study. The 11-Point-Box-Test showed a significant decrease of pain under Nabilone (p < 0.05), while spasticity, motor function and activities of daily living did not change. 5 patients reported side effects: one moderate transient weakness of the lower limbs (Nabilone phase, drop out), three mild drowsiness (two Nabilone, one placebo) and one mild dysphagia (placebo). One patient was excluded from the study due to an acute relapse of multiple sclerosis (Nabilone phase, drop out). Nabilone 1 mg per day proved to be a safe and easily applicable option in the care of patients with chronic UMNS and spasticity-related pain otherwise not controllable.

Activities of Daily Living↗
PubMed2006

Antibodies as biological markers for pathophysiological processes in MS.

Multiple sclerosis (MS), the most important human inflammatory demyelinating disease of the central nervous system, is characterized by various clinical disease courses, inhomogeneous and unpredictable therapeutic effects, heterogenous genetic backgrounds and immunopathogenetic subtypes as demonstrated by neuropathology. Because of this heterogeneity of MS, a subtyping of our patients by genetical, clinical, neuroradiological, and neuroimmunological parameters will be necessary in the future. Therefore the importance of identifying biological markers for MS has evolved over the past years. Evidence for a possible role of antibodies as biological markers for MS comes from several studies indicating that intrathecal antibody production and the dominance of B cells are associated with a more progressive disease course. In this review we will give an overview on the current status and potential applicability of antibodies as biological markers for the diagnosis, classification, disease activity and prediction of clinical courses in MS. We will therefore summarize the findings on autoantibodies to myelin and nonmyelin antigens and on viral antigens in MS. We believe that antibodies serving as biomarkers will help to establish a differential therapeutic concept in MS, which will allow to treat individuals selectively according to their pathogenetic subtype and disease status.

Animals↗
PubMed2006

The efficiency of various thermoluminescence dosemeter types to heavy ions.

Dose verification in heavy-ion beams using passive dosemeter systems, e.g. thermoluminescence dosemeters (TLDs), is crucial due to the changing efficiency of the dosemeters for different ion species and linear energy transfer (LET) values. This behaviour leads to a falsification of absorbed dose that can be significant for many applications, e.g. in space or radiotherapeutic dosimetry. TLDs can only be established as a 'reference' system in heavy-ion beams or other radiation fields if the efficiency functions for all contributing ion species and LET values are provided. In the framework of a research project of the Atominstitute of the Austrian Universities irradiations with various ions were performed in the years 2001-2003 at the Heavy Ion Medical Accelerator (HIMAC) of the National Institute for Radiological Sciences (NIRS) in Chiba, Japan. Efficiency values were recorded in dependence on ion species and LET in a range from 2 to 400 keV microm(-1). The efficiencies of five different commercially available TLD materials namely TLD 600, TLD 700, TLD 700H, TLD 300 and TLD 200 were investigated.

Dose-Response Relationship, Radiation↗
PubMed2006

Efficiency-corrected dose verification with thermoluminescence dosemeters in heavy-ion beams.

One of the most essential difficulties in heavy-ion dosimetry by means of thermoluminescence dosemeters (TLDs)--often seen as a serious disadvantage of TLD utilisation--regards the changing TL-efficiency with increasing linear energy transfer (LET) of the particle. This behaviour leads to a falsification of absorbed dose that can be significant for many applications, e.g. in space or radiotherapeutic dosimetry. The high-temperature TL emission of LiF:Mg,Ti TL detectors can be exploited to obtain information about the LET of the heavy-ion radiation field under study. The high-temperature ratio (HTR) is used as a parameter to determine average LET. To correct the absorbed dose according to the TL-efficiency, the detailed dependence of HTR- and TL-efficiency on LET was recorded. These investigations were accomplished at the Heavy Ion Medical Accelerator (HIMAC) in Chiba, Japan, with a variety of high-energy ion beams (helium, carbon, neon, silicon and iron) ranging in LET from 2.2 to 393 keV microm(-1). The obtained relationships HTR vs. LET and TL-efficiency vs. LET were combined into a TL efficieny vs. HTR relationship. This enables correction of the absorbed dose (HTR-B method). The methodology is demonstrated by means of TLD 700 ((7)LiF:Mg,Ti) measurements in carbon beams of 290 and 400 MeV n(-1) available from HIMAC.

Algorithms↗
PubMed2006

The MATROSHKA facility--dose determination during an EVA.

On 29 January 2004 the MATROSHKA facility was launched with a Russian Progress to the International Space Station. MATROSHKA is an ESA project, which has been achieved under the direction of the German Aerospace Center (DLR). The project is a cooperation of >16 research institutes from all over the world and is currently the biggest international experiment in radiation dosimetry ever performed in space. The facility simulates, as exact as possible, an astronaut during an extravehicular activity. It was successfully installed outside the Russian segment 'Zvezda' on 26 February 2004 and will remain there for a 1.5 year exposure period. The main task of the facility is to measure particle fluence and energy spectra, dose and dose rates outside and inside--including organ dose determination--in an anthropomorphic phantom mounted on the outside of the Space Station with passive and active dosemeter systems.

Body Burden↗
PubMed2006

Particles coming together: electron centers in adjoined TiO2 nanocrystals.

To include particle attachment and porosity of nanostructured materials in the discussion of their electronic properties is critical to our understanding of charge transfer across grain boundaries. We report the condensation of isolated TiO(2) nanocrystals via the application of a simple hydration-dehydration cycle. After contact with water and subsequent removal of adsorbed water, these nanocrystals form a mesoporous structure with altered properties as compared with the original material: first, the energy needed for defect formation is substantially reduced, and second, electron paramagnetic resonance measurements reveal the presence of polarizable conduction band electrons not detectable in samples which have not been in contact with water.

Journal Article↗
PubMed2006

HLA-B8 association with late-stage melanoma--an immunological lesson?

BACKGROUND: Differences in HLA allele frequencies between the diseased and healthy populations may signify efficient immune responses, a notion that has been successfully tested for infectious diseases or for association with genetic elements involved in a distinct type of immunity. This retrospective study is intended to detect differences in MHC class I carrier frequencies of advanced melanoma patients compared to healthy bone marrow donors. METHODS: The HLA-A and -B carrier frequencies of 748 stage IV melanoma patients retrieved from serotyping at 6 different centers in Germany were compared using a chi-square test to 13,386 fully HLA typed bone marrow donors registered in the German national bone marrow donor registry. RESULTS: The comparison of HLA carrier frequencies in advanced cancer patients with healthy bone marrow donors revealed a significant decrease in HLA-B8 carrier frequencies, which was also apparent in patients with advanced disease compared to patients with loco-regional disease. CONCLUSION: The data suggest that protective immune responses restricted to distinct MHC class I molecules may be operational in a subset of melanoma patients, which is the prerequisite for a large scale screen for the corresponding epitopes. Alternatively, the known association of the ancestral haplotype HLA-A1, -B8 and -DR3 with genetic elements such as distinct TNF-alpha alleles might have a protective effect on disease progression. In any case, identification of the cause of protection within this patient subset might lead to a significant improvement in the efficacy of current immunotherapeutic approaches.

Gene Frequency↗
PubMed2006

Epitope specificity of serum antibodies directed against the extracellular domain of myelin oligodendrocyte glycoprotein: Influence of relapses and immunomodulatory treatments.

Only few reports are available on the epitope specificity of anti-myelin oligodendrocyte glycoprotein (MOG) antibodies in multiple sclerosis (MS). In the present study we provide a precise characterization of the epitope specificity of serum antibodies directed against the extracellular domain of MOG, including IgG, IgM and IgA immunoglobulin isotypes in 28 relapsing remitting MS patients and report that linear epitopes amino-acid (aa) 37-48 and aa42-53 are immunodominant. Recently experienced relapses intensified the anti-MOG peptide antibody response. Immunomodulatory treatment with interferon-beta or glatiramer-acetate had no major impact on the anti-MOG peptide immunoreactivity after 1 year of therapy.

Adult↗
PubMed2006

UV induced local heating effects in TiO2 nanocrystals.

When isolated TiO(2) nanocrystals are subjected to UV light at 77 K and pressures below 10(-6) mbar, trapping of photogenerated hole centers occurs on the surface of the nanocrystals and can be tracked by time-resolved electron paramagnetic resonance spectroscopy. Irrespective of the selected UV irradiance used, the maximum concentration of trapped charges was found to be constant for a given number of nanocrystals ( approximately 10(15)) and corresponds to one electron-hole pair per particle. On a time scale of seconds to minutes the dynamics for the trapping process depend on the number of photons with supra band gap energy. A local temperature rise of the TiO(2) nanocrystals was observed for irradiances above 1.55 mW cm(-2) (10(15) photons cm(-2) s(-1)). This is attributed to enhanced nonradiative recombination of photogenerated charge carriers via heat production and points to a substantial contribution of thermal chemistry in photocatalytic reaction cycles.

Electron Spin Resonance Spectroscopy↗
PubMed2006

New efficient stimuli for evoking frequency-specific auditory steady-state responses.

ASSR is a promising tool for the objective frequency-specific assessment of hearing thresholds in children. The stimulus generally used for ASSR recording (single amplitude-modulated carrier) only activates a small area on the basilar membrane. Therefore, the response amplitude is low. A stimulus with a broader frequency spectrum can be composed by adding several cosines whose frequency intervals comply with the desired stimulus repetition rate. Compensation of the travelling wave delay on the basilar membrane is possible with a stimulus of this type. Through this, a better synchronization of the neural response can be obtained and, as a result, higher response amplitudes can be expected, particularly for low-frequency stimuli. The additional introduction of a frequency offset enables the use of a q-sample test for the response detection, especially important at 500 Hz. The results of investigations carried out on a large group of normally hearing test subjects have confirmed the efficiency of this stimulus design. The new stimuli lead to significantly improved ASSRs with higher SNRs and thus higher detection rates and shorter detection times.

Acoustic Stimulation↗
PubMed2005

Use of mucosal immunization with porcine zona pellucida (PZP) in mice and rabbits.

Rabbits (Oryctolagus cuniculus) and two strains of mice (Mus musculus, one inbred and one outbred) were immunized against porcine zona pellucida (PZP) antigen. Alginate microspheres or cholera toxin B were used alone or in combination when mucosal immunization routes were used. Serum antibody responses and fertility were assessed. Neither rabbit or mouse groups immunized by mucosal routes generated significant antibody responses to PZP as compared to parenteral immunization (ANOVA, P > 0.05). The study shows that porcine zona pellucida is not an effective mucosal antigen in small mammals.

Administration, Oral↗
PubMed2005

Charge trapping and photoadsorption of O2 on dehydroxylated TiO2 nanocrystals--an electron paramagnetic resonance study.

The interaction of photogenerated charges with molecular oxygen was investigated on TiO2 nanocrystals by means of paramagnetic resonance (EPR) spectroscopy. Compared to photoactivation experiments in vacuum at P < 10(-6) mbar and T = 140 K, the presence of O2 enhances the concentration of persistently trapped electron and hole centres--by a factor of ten--due to the formation of adsorbed O2- species. The photoadsorption of oxygen was also tracked quantitatively by pressure measurements, and the number of trapped charges, hole centres and O2- was found to correspond to ten electron-hole pairs per TiO2 nanocrystal. Conversely, in experiments at P < 10(-6) mbar with one trapped electron-hole pair per particle, charge separation is not persistent and completely reversible with respect to temperature. Heating to 298 K causes the total annihilation of photogenerated and trapped charges.

Journal Article↗
PubMed2005

Chemistry at corners and edges: generation and adsorption of H atoms on the surface of MgO nanocubes.

We used UV light to generate site-selective O- hole centers at three-coordinated corner oxygen sites on MgO nanocubes. These highly reactive O- radicals split H2 homolytically and, in the course of this reaction, become hydroxylated and produce hydrogen atoms. The hydrogen atoms adsorb predominantly at cube edges and dissociate into surface-trapped electrons and protons. We propose that the experimentally observed (H+)(e-) centers are formed adjacent to the hydroxyl groups generated in the homolytic splitting process and can be defined as (H+)3C...(e-)(H+)NC centers where 3C and NC refer to the coordination numbers of the corresponding hydroxylated oxygen sites. Our ab initio embedded cluster calculations reveal that the electronic properties of (H+)3C...(e-)(H+)4C centers situated along MgO nanocube edges are consistent with both the electron-paramagnetic-resonance signal parameters and the reported optical-absorption properties. The transformation of corner O- centers into the (H+)3C...(e-)(H+)NC-type centers prevents their recombination with electronic surface centers and, hence, significantly alters the electronic structure of MgO nanocubes by introducing shallow electron traps.

Journal Article↗
PubMed2005

Daytime sleepiness is not increased in mild to moderate multiple sclerosis: a pupillographic study.

BACKGROUND: Daytime sleepiness has been described in multiple sclerosis (MS); a combination of MS and narcolepsy has also been observed in a few case reports. In this study, we investigated daytime sleepiness in a general sample of MS patients compared to healthy controls with the pupillographic sleepiness test (PST) and the Epworth and Stanford sleepiness scales (ESS, SSS). METHODS: A PST was performed in consecutive MS patients and controls. Additionally, a questionnaire including the ESS and the SSS was applied. RESULTS: Sixty-one MS patients (29 men and 32 women, age 34.5+/-8.3 years, mean disease duration 7.4+/-6.6 years, expanded disability status scale (EDSS) 1.7+/-1.2 (mean +/- sd)) and 42 age-matched controls (13 men and 29 women, age 36.9+/-12.9 years) participated in this study. In the MS group, the pupillary unrest index (PUI) was 5.0+/-2.0, the ESS 7.4+/-3.5 and the SSS 2.4+/-1.2, whereas in the control group, the PUI was 4.7+/-1.8, the ESS 8.4+/-4.0 and the SSS 2.4+/-1.2 (mean +/- sd). These differences were not significant. No correlation was found between PUI and the ESS or the SSS. Furthermore, no correlation was found between EDSS and sleepiness measured by PUI, ESS and SSS. CONCLUSION: In a general sample of MS patients with mild to moderate disease, there was no evidence for overall increased daytime sleepiness compared to healthy controls.

Adult↗
PubMed2005

The effect of nabilone on neuropsychological functions related to driving ability: an extended case series.

The primary goal of this prospective extended case series was to obtain the first data about the potential influence of nabilone intake on driving ability related neuropsychological functions. Six patients were investigated within a placebo controlled, double-blind crossover study of this synthetic cannabinoid (2 mg/day) in patients with multiple sclerosis and spasticity associated pain. Five neuropsychological functions (reaction time, working memory, divided attention, psychomotor speed and mental flexibility) were assessed. No indication was found of a deterioration of any of the five investigated neuropsychological functions during the 4-week treatment period with nabilone.

Adult↗
PubMed2005

Multiple disseminated large-cell acanthomas of the skin associated with human papillomavirus type 6.

Cutaneous acanthomas encompass many clinically distinct types. We describe a patient with multiple nodules on the skin of the upper limbs which were histologically diagnosed as large-cell acanthomas. Further analysis revealed, surprisingly, the presence of human papillomavirus (HPV) type 6 within these lesions. HPV type 6 should therefore be considered an important cofactor in the pathogenesis of large-cell acanthomas.

Acanthoma↗