Showing papers by "University of Jena published in 2000"

Treatment-Induced Cortical Reorganization After Stroke in Humans

Abstract: Background and Purpose—Injury-induced cortical reorganization is a widely recognized phenomenon. In contrast, there is almost no information on treatment-induced plastic changes in the human brain. The aim of the present study was to evaluate reorganization in the motor cortex of stroke patients that was induced with an efficacious rehabilitation treatment. Methods—We used focal transcranial magnetic stimulation to map the cortical motor output area of a hand muscle on both sides in 13 stroke patients in the chronic stage of their illness before and after a 12-day-period of constraint-induced movement therapy. Results—Before treatment, the cortical representation area of the affected hand muscle was significantly smaller than the contralateral side. After treatment, the muscle output area size in the affected hemisphere was significantly enlarged, corresponding to a greatly improved motor performance of the paretic limb. Shifts of the center of the output map in the affected hemisphere suggested the recru...

Xylan and xylan derivatives – biopolymers with valuable properties, 1. Naturally occurring xylans structures, isolation procedures and properties

Abstract: The availability of xylan-type polysaccharides, representing an immense resource of biopolymers for practical application, is summarized. Xylans constitute 25–35% of the dry biomass of woody tissues of dicots and lignified tissues of monocots and occur up to 50% in some tissues of cereal grains. The most potential sources of xylans include many agricultural crops such as straw, sorghum, sugar cane, corn stalks and cobs, hulls and husks from starch production, as well as forest and pulping waste products from hardwoods, in particular. The structural diversity and complexity of xylans is illustrated and shown to depend on the botanic source. Various extraction procedures suitable for the isolation of xylans from different plant sources are described and compared. It is suggested that certain structural types of xylans like glucuronoxylan, arabinoglucuronoxylan, and arabinoxylan can be prepared from certain plant sources with similar chemical and physical properties. In contrast to structural analyses, the physicochemical properties, including solubility, molecular weight and molecular weight distribution, and rheological properties have been studied only for few xylan types. From the functional properties, the thermophysical and tensioactive properties are described. Finally, the physiological activities of xylans, which represent important dietary fibers as well as the immunological activities of some xylan types, are presented.

Multicenter investigation of 1,036 subjects using a standardized method for the assessment of olfactory function combining tests of odor identification, odor discrimination, and olfactory thresholds.

Abstract: “Sniffin’ Sticks” is a test of nasal chemosensory performance that is based on penlike odor-dispensing devices. It is comprised of three tests of olfactory function: tests for odor threshold, discrimination and identification. Previous work has already established its test-retest reliability and validity in comparison to established measures of olfactory sensitivity. The results of this test are presented as a composite TDI score – i.e., the sum of results obtained for threshold, discrimination and identification measures. The present multicenter investigation aimed at providing normative values in relation to different age groups. To this end, 966 patients were investigated in 11 centers. An additional study tried to establish values for the identification of anosmic patients, with 70 anosmics investigated in five specialized centers where the presence of anosmia was confirmed by means of olfactory evoked potentials. For healthy subjects, the TDI score at the 10th percentile was 24.5 in subjects younger than 15 years, 30.3 for ages from 16 to 35 years, 28.8 for ages from 36 to 55 years and 27.5 for subjects older than 55 years. While these data can be used to estimate individual olfactory abilities in relation to a subject’s age, hyposmia was defined as the 10th percentile score of 16- to 35-year-old subjects. Our latter study revealed that none of 70 anosmics reached a TDI score higher than 15. This score of 15 is regarded as the cut-off value for functional anosmia. These results provide the basis for the routine clinical evaluation of patients with olfactory disorders using “Sniffin’ Sticks.”

Macrophages in rheumatoid arthritis

Abstract: The abundance and activation of macrophages in the inflamed synovial membrane/pannus significantly correlates with the severity of rheumatoid arthritis (RA). Although unlikely to be the 'initiators' of RA (if not as antigen-presenting cells in early disease), macrophages possess widespread pro-inflammatory, destructive, and remodeling capabilities that can critically contribute to acute and chronic disease. Also, activation of the monocytic lineage is not locally restricted, but extends to systemic parts of the mononuclear phagocyte system. Thus, selective counteraction of macrophage activation remains an efficacious approach to diminish local and systemic inflammation, as well as to prevent irreversible joint damage.

Assessment of cardiac preload and extravascular lung water by single transpulmonary thermodilution.

Abstract: Objective: Transpulmonary double-indicator dilution is a useful monitoring technique for measurement of intrathoracic blood volume (ITBV) and extravascular lung water (EVLW). In this study, we compared a simpler approach using single arterial thermodilution derived measurements of ITBV and EVLW with the double-indicator dilution technique.¶Design: Prospective observational clinical study.¶Setting: Surgical intensive care units of two university hospitals.¶Patients and methods: Global end-diastolic volume (GEDV) derived from single thermodilution was used for calculation of ITBV. Structural regression analysis of the first two thermo-dye dilution measurements in a derivation population of 57 critically ill patients (38 male, 19 female, 18–79 years, 56 ± 15 years) revealed ITBV = (1.25 · GEDV)–28.4 (ml). This equation was then applied to all first measurements in a validation population of 209 critically ill patients (139 male, 70 female, 10–88 years, mean 53 ± 19 years), and single-thermodilution ITBV (ITBVST) and EVLW (EVLWST) was calculated and compared to thermo-dye dilution derived values (ITBVTD, EVLWTD). For inter-individual comparison, absolute values for ITBV and EVLW were normalised as indexed by body surface area (ITBVI) and body weight (EVLWI), respectively.¶Measurements and results: Linear regression analysis yielded a correlation of ITBVIST = (1.05 · ITBVITD)–58.0 (ml/m2), r = 0.97, P < 0.0001. Bias between ITBVITD and ITBVIST was 7.6 (ml/m2) with a standard deviation of 57.4 (ml/m2). Single-thermodilution EVLWI (EVLWIST) was calculated using ITBVIST and revealed the correlation EVLWIST = (0.83 · EVLWITD) + 1.6 (ml/kg), r = 0.96, P < 0.0001. Bias between EVLWITD and EVLWIST was –0.2 (ml/kg) with a standard deviation of 1.4 (ml/kg). In detail, EVLWIST systematically overestimated EVLWITD at low-normal values for EVLWI and underestimated EVLWI at higher values (above 12 ml/kg).¶Conclusion: Determinations of ITBV and EVLW by single thermodilution agreed closely with the corresponding values from the double-indicator technique. Since transpulmonary single thermodilution is simple to apply, less invasive and cheaper, all these features make it a promising technique for the bedside. Nevertheless, further validation studies are needed in the future.

Cyanobacterial Cell Walls: News from an Unusual Prokaryotic Envelope

Abstract: Most modern reviews about bacterial cell wall properties use the traditional classification of prokaryotic envelopes as either gram positive or gram negative ([27][1], [30][2]). Mainly based on the variance of their peptidoglycan architecture, both envelope types show a characteristic difference

Biotechnology and the European public

Abstract: The latest European sample survey of public perceptions of biotechnology reveals widespread opposition to genetically modified (GM) food in much of Europe, but public attitudes to medical and environmental applications remain positive.

The critical laser intensity of self-guided light filaments in air

Abstract: The critical intensity inside plasma filaments generated in air by high-power, ultra-short laser pulses is estimated analytically and compared to recent experimental data. The result, Icrit≈4×1013 W/cm2, is highly relevant for atmospheric applications.

The migration and growth of protoplanets in protostellar discs

Abstract: ABSTRA C T We investigate the gravitational interaction of a Jovian-mass protoplanet with a gaseous disc with aspect ratio and kinematic viscosity expected for the protoplanetary disc from which it formed. Different disc surface density distributions are investigated. We focus on the tidal interaction with the disc with the consequent gap formation and orbital migration of the protoplanet. Non-linear two-dimensional hydrodynamic simulations are employed using three independent numerical codes. A principal result is that the direction of the orbital migration is always inwards and such that the protoplanet reaches the central star in a near-circular orbit after a characteristic viscous time-scale of ,10 4 initial orbital periods. This is found to be independent of whether the protoplanet is allowed to accrete mass or not. Inward migration is helped by the disappearance of the inner disc, and therefore the positive torque it would exert, because of accretion on to the central star. Maximally accreting protoplanets reach about 4 Jovian masses on reaching the neighbourhood of the central star. Our results indicate that a realistic upper limit for the masses of closely orbiting giant planets is ,5 Jupiter masses, if they originate in protoplanetary discs similar to the minimum-mass solar nebula. This is because of the reduced accretion rates obtained for planets of increasing mass. Assuming that some process such as termination of the inner disc through a magnetospheric cavity stops the migration, the range of masses estimated for a number of close orbiting giant planets as well as their inward orbital migration can be accounted for by consideration of disc‐protoplanet interactions during the late stages of giant planet formation.

Fraction of Condensed Counterions around a Charged Rod: Comparison of Poisson−Boltzmann Theory and Computer Simulations

Abstract: We investigate the phenomenon of counterion condensation in a solution of highly charged rigid polyelectrolytes within the cell model. A method is proposed whichbased on the charge distribution functionidentifies both the fraction of condensed ions and the radial extension of the condensed layer. Within salt-free Poisson−Boltzmann (PB) theory it reproduces the well-known fraction 1−1/ξ of condensed ions for a Manning parameter ξ > 1. Furthermore, it predicts a weak salt dependence of this fraction and a breakdown of the concept of counterion condensation in the high-salt limit. We complement our theoretical investigations with molecular dynamics simulations of a cell-like model, which constantly yield a stronger condensation than predicted by PB theory. While the agreement between theory and simulation is excellent in the monovalent, weakly charged case, it deteriorates with increasing electrostatic interaction strength and, in particular, increasing valence. For instance, at a high concentration of dival...

Remote sensing of the atmosphere using ultrashort laser pulses

Abstract: Theoretical and experimental studies were performed on the propagation of ultrashort optical terawatt pulses through the atmosphere. Propagation simulations of intense sub-picosecond pulses show that non-linear processes, such as white light generation, can be initiated at a chosen distance by selecting an appropriate group velocity dispersion. With this technique, a white light continuum was generated in the atmosphere whose spectral distribution was characterised in the visible and near infra-red. Applications of this novel light source for atmospheric remote sensing were investigated, combining lidar and time-resolved broadband absorption spectroscopy techniques. Measurements were performed on the oxygen molecule and water vapour. A comparison between the experimental results and the tabulated spectroscopic data led to an excellent correlation with measurements made on water vapour whereas observations on the oxygen showed discrepancy. This study demonstrates that the remote generation of a white light source represents a new way to access the range-resolved multi-trace gas analysis in the atmosphere.

Effective preparation of cellulose derivatives in a new simple cellulose solvent

Abstract: Full Paper: Ceflulore with a degree of polymerization up to 650 can be dissolved in dimethyl sulfoxide containing 10 to 20% (w/v: tetrabutylammonium floride trihydrate without any pretreatment within15 min at room temperature. The new solvent can be classified as a non-derivatizing one as concluded from 13 C NMR measurements. The solvent can be used as reaction medium for the homogeneous functionalization of the polymer. Cellulose esters are prepared very effective by transesterification reactions. The functional groups are deistributed in the order expected for a homogeneous conversion, i. e., a preferred reaction at the primary hydroxyl groups occurs. Moreover, carboxymethyl cellulose with a preferred functionalization at the primary hydroxyl groups and a nonstatic content of the different repeating units was accessible.

Effects of antagonists to high-threshold calcium channels upon spinal mechanisms of pain, hyperalgesia and allodynia.

Abstract: High-threshold voltage-dependent calcium channels enable calcium ions to enter neurons upon depolarization and thereby influence synaptic mediator/receptor systems, membrane excitability levels, second and third messenger concentration, and gene expression. These phenomena underlie several processes including those of normal nociception and of hyperalgesia and allodynia. The present article deals with the role of spinal L-, N- and P/Q-type calcium channels in short-lasting nociception as well as in the hyperalgesia and allodynia elicited by chemical irritants of peripheral nociceptors, inflammatory and mechanical lesions of peripheral tissues, and lesions of peripheral nerves. The studies summarized herein are based on the spinal delivery of specific antagonists to high-threshold calcium channels, and reveal that blockade of L-type, P/Q-type and, particularly, N-type channels can prevent, attenuate, or both, subjective pain as well as primary and/or secondary hyperalgesia and allodynia in a variety of experimental and clinical conditions.

Growth and form of planetary seedlings: results from a microgravity aggregation experiment.

Abstract: The outcome of the first stage of planetary formation, which is characterized by ballistic agglomeration of preplanetary dust grains due to Brownian motion in the free molecular flow regime of the solar nebula, is still somewhat speculative. We performed a microgravity experiment flown onboard the space shuttle in which we simulated, for the first time, the onset of free preplanetary dust accumulation and revealed the structures and growth rates of the first dust agglomerates in the young solar system. We find that a thermally aggregating swarm of dust particles evolves very rapidly and forms unexpected open-structured agglomerates.

Screening for high‐grade cervical intra‐epithelial neoplasia and cancer by testing for high‐risk HPV, routine cytology or colposcopy

Abstract: The validity of testing for high-risk types of human papillomavirus (HPV) in cervical cancer prevention programs is undetermined We compared the performance on primary screening of HPV DNA testing, cytology and colposcopy in detecting cervical intra-epithelial neoplasia (CIN) grade 2 or 3 or cancer A cohort of 4,761 women, median age 35 years, was screened by routine cytology, routine colposcopy and testing for high-risk HPV by a PCR-based method Within an 8-month period, women with abnormal findings on cytology or screening colposcopy or in whom high-risk HPV types were detected were referred for colposcopy and biopsy Women negative on all initial screening tests were followed by a second screening examination To correct for work-up bias, the true prevalence of CIN 2 or 3 or cancer was estimated by projection from histologically verified subgroups Cervical biopsies were taken in 364 women (76%), of whom 114 (24%) showed CIN 2 (n = 34) or CIN 3 (n = 71) or cancer (n = 9) High-risk HPV testing achieved bias-corrected performance measures of 894% sensitivity, 939% specificity, 358% positive predictive value and 996% negative predictive value Bias-corrected rates of true- and false-positives by high-risk HPV testing compared to cytology (colposcopy) were about 45 (67) and 191 (74) times higher, respectively The quality of routine cytology was controlled by computer-assisted review, and the observed number of true-positives more than doubled after adding automated review results In middle-aged women, testing for high-risk HPV types, particularly when negative, may be used to increase the screening interval in programs for secondary prevention of cervical cancer

Analogous experiments on the stickiness of micron-sized preplanetary dust

Abstract: In the early solar nebula, the formation of planetesimals and cometesimals is believed to be due to inelastic collisions of initially micron-sized grains. The collisions are caused by relative velocities due to size-dependent interactions with the surrounding dilute gas. The grain growth process is determined by the velocity-dependent sticking efficiency upon collisions. Therefore, we performed experiments with eight samples of micron-sized particles consisting of monodisperse silica spheres, of irregularly shaped diamond, enstatite, and silicon carbide grains, and of silicon carbide whiskers. We determined the sticking probability and the energy loss upon bouncing collisions by studying individual grain-target collisions in vacuum. We found a sticking probability higher than predicted by previous theoretical work. Grain size, roughness, and primarily grain shape, i.e., the difference of spherical versus irregular grain shape, is important for the collisional behavior, whereas the material properties are rather unimportant. Our results indicate that the preplanetary dust aggregation is more effective than previously thought.

Oral naloxone reverses opioid-associated constipation

Abstract: Opioid-related constipation is one of the most frequent side effects of chronic pain treatment. Enteral administration of naloxone blocks opioid action at the intestinal receptor level but has low systemic bioavailability due to marked hepatic first-pass metabolism. The aim of this study was to examine the effects of oral naloxone on opioid-associated constipation in an intraindividually controlled manner. Twenty-two chronic pain patients with oral opioid treatment and constipation were enrolled in this study. Constipation was defined as lack of laxation and/or necessity of laxative therapy in at least 3 out of 6 days. Laxation and laxative use were monitored for the first 6 days without intervention ('control period'). Then, oral naloxone was started and titrated individually between 3x3 to 3x12 mg/day depending on laxation and withdrawal symptoms. After the 4-day titration period, patients were observed for further 6 days ('naloxone period'). The Wilcoxon signed rank test was used to compare number of days with laxation and laxative therapy in the two study periods. Of the 22 patients studied, five patients did not reach the 'naloxone period' due to death, operation, systemic opioid withdrawal symptoms, or therapy-resistant vomiting. In the 6 day 'naloxone' compared to the 'control period', the mean number of days with laxation increased from 2.1 to 3.5 (P<0.01) and the number of days with laxative medication decreased from 6 to 3.8 (P<0.01). The mean naloxone dose in the 'naloxone period' was 17.5 mg/day. The mean pain intensity did not differ between these two periods. Moderate side effects of short duration were observed in four patients following naloxone single dose administrations between 6 and 20 mg, resulting in yawning, sweating, and shivering. Most of the patients reported mild or moderate abdominal propulsions and/or abdominal cramps shortly after naloxone administration. All side effects terminated after 0.5-6 h. This controlled study demonstrates that orally administered naloxone improves symptoms of opioid associated constipation and reduces laxative use. To prevent systemic withdrawal signs, therapy should be started with low doses and patients carefully monitored during titration.

MR venography of multiple sclerosis.

Abstract: BACKGROUND AND PURPOSE: The distribution of multiple sclerosis (MS) lesions in the brain follows a specific pattern, with most lesions in the periventricular regions and in the deep white matter; histopathologic studies have shown a perivenous distribution. The aim of this study was to illustrate these distribution patterns in vivo using high-resolution MR venography. METHODS: Seventeen MS patients underwent MR imaging at 1.5 T. Venographic studies were obtained with a 3D gradient-echo technique. MS lesions were identified on T2-weighted images, and their shape, orientation, and location were compared with the venous anatomy on the venograms. RESULTS: The use of contrast material facilitated the visualization of small veins and increased the number of veins seen. A total of 95 MS lesions could be identified on both the T2-weighted series and the venograms; a central vein was visible in all 43 periventricular lesions and in all but one of the 52 focal deep white matter lesions. The typical ovoid shape and orientation of the long axis of the MS lesions correlated well with the course of these veins. CONCLUSION: With MR venography, the perivenous distribution of MS lesions in the brain can be visualized in vivo. The venous anatomy defines the typical form and orientation of these lesions.

High-resolution MR venography at 3.0 Tesla.

Abstract: Purpose: The aim of this study was to investigate the visualization of small venous vessels in the normal human brain at a field strength of 3 Tesla. Methods: T2 * -weighted, three-dimensional gradient-echo images were acquired by exploiting the magnetic susceptibility difference between oxygenated and deoxygenated hemoglobin in the vasculature and microvasculature. The spatial resolution was 0.5 x 0.5 x 1 mm 3 , and sequence parameters were varied to obtain good vessel delineation. Improved visibility of venous vessels was obtained by creating phase mask images from the magnetic resonance phase images and multiplying these by the magnitude images. Venograms were created by performing a minimum intensity projection over targeted volumes. Results: Highly detailed visualization of venous structures deep in the brain and in the superficial cortical areas were obtained without administration of an exogenous contrast agent; compared with similar studies performed at 1.5 T, the echo time could be reduced from typically 40-50 ms to 17-28 ms. Conclusion: Imaging at high-field strength offers the possibility of improved resolution and the delineation of smaller vessels compared with lower field strengths.

Training-induced changes of motor cortex representations in stroke patients.

Abstract: Objective - To study changes in motor cortex representations after a single session of physiotherapy in stroke patients Methods - TMS mapping was used to evaluate the motor output map of the abductor pollicis brevis (APB) in both hemispheres Stroke patients (4-8 weeks after the infarction) were studied prior to a training session aimed at improving dexterity and 1 h and 1 day after the training Results - Prior to the training, the APB representation area in the affected hemisphere was significantly smaller than on the non-affected side After therapy, the cortical motor output to the paretic APB was significantly enlarged, and motor function was improved One day later, these effects were partially reversed Motor thresholds remained significantly increased in the affected hemisphere before and after the therapy Conclusion - A single session of physiotherapy produces a use-dependent enlargement of motor cortex representations paralleled by an improvement of motor function in stroke patients

Spontaneous decay in the presence of dispersing and absorbing bodies: General theory and application to a spherical cavity

Abstract: A formalism for studying spontaneous decay of an excited two-level atom in the presence of dispersing and absorbing dielectric bodies is developed An integral equation, which is suitable for numerical solution, is derived for the atomic upper-state-probability amplitude The emission pattern and the power spectrum of the emitted light are expressed in terms of the Green tensor of the dielectric-matter formation, including absorption and dispersion The theory is applied to the spontaneous decay of an excited atom at the center of a three-layered spherical cavity, with the cavity wall being modeled by a band-gap dielectric of Lorentz type Both weak and strong coupling are studied, the latter with a special emphasis on cases where the atomic transition is (i) in the normal-dispersion zone near the medium resonance, and (ii) in the anomalous-dispersion zone associated with the band gap In a single-resonance approximation, conditions of the appearance of Rabi oscillations and closed solutions to the evolution of the atomic state population are derived, which are in good agreement with the exact numerical results

Yield Optimization and Time Structure of Femtosecond Laser Plasma K α Sources

Abstract: The generation of femtosecond $K\ensuremath{\alpha}$ x rays from laser-irradiated plasmas is studied with a view to optimizing photon number and pulse duration. Using analytical and numerical models of hot electron generation and subsequent transport in a range of materials, it is shown that an optimum laser intensity ${I}_{\mathrm{opt}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}7\ifmmode\times\else\texttimes\fi{}{10}^{9}{Z}^{4.4}$ exists for maximum $K\ensuremath{\alpha}$ yield. Furthermore, it is demonstrated that bulk targets are unsuitable for generating sub-ps x-ray pulses: instead, design criteria are proposed for achieving $K\ensuremath{\alpha}$ pulse durations $\ensuremath{\le}100\mathrm{fs}$ using foils of $\ensuremath{\approx}2\ensuremath{\mu}\mathrm{m}$ thickness.

From Cadomian subduction to Early Palaeozoic rifting: the evolution of Saxo-Thuringia at the margin of Gondwana in the light of single zircon geochronology and basin development (Central European Variscides, Germany)

Abstract: Abstract Saxo-Thuringia is classified as a tectonostratigraphic terrane belonging to the Armorican Terrane Collage (Cadomia). As a former part of the Avalonian-Cadomian Orogenic Belt, it became (after Cadomian orogenic events, rift-related Cambro-Ordovician geodynamic processes and a northward drift within Late Ordovician to Early Silurian times), during Late Devonian to Early Carboniferous continent-continent collision, a part of the Central European Variscides. By making use of single zircon geochronology, geochemistry and basin analysis, geological processes were reconstructed from latest Neoproterozoic to Ordovician time: (1) 660–540 Ma: subduction, back-arc sedimentation and tectonomagmatic activity in a Cadomian continental island-arc setting marginal to Gondwana; (2) 540 Ma: obduction and deformation of the island arc and marginal basins; (3) 540–530 Ma: widespread plutonism related to the obduction-related Cadomian heating event and crustal extension; (4) 530–500 Ma: transform margin regime connected with strike-slip generated formation of Early to Mid-Cambrian pull-apart basins; (5) 500–490 Ma: Late Cambrian uplift and formation of a chemical weathering crust; (6) 490–470 Ma: Ordovician rift setting with related sedimentation regime and intense igneous activity; (7) 440–435 Ma: division from Gondwana and start of northward drift. The West African and the Amazonian Cratons of Gondwana, as well as parts of Brittany, were singled out by a study of inherited and detrital zircons as potential source areas in the hinterland of Saxo-Thuringia.

Isolation and characterization of rheumatoid arthritis synovial fibroblasts from primary culture — primary culture cells markedly differ from fourth-passage cells

Abstract: To reduce culture artifacts by conventional repeated passaging and long-term culture in vitro, the isolation of synovial fibroblasts (SFB) was attempted from rheumatoid arthritis (RA) synovial membranes by trypsin/collagenase digest, short-term in vitro adherence (7 days), and negative isolation using magnetobead-coupled anti-CD14 monoclonal antibodies. This method yielded highly enriched SFB (85% prolyl-4-hydroxylase+/74% Thy-1/CD90+ cells; <2% contaminating macrophages; <1% leukocytes/endothelial cells) that, in comparison with conventional fourth-passage RA-SFB, showed a markedly different phenotype and significantly lower proliferation rates upon stimulation with platelet-derived growth factor and IL-1β. This isolation method is simple and reliable, and may yield cells with features closer to the in vivo configuration of RA-SFB by avoiding extended in vitro culture.