Toscana virus encephalitis in Southwest Germany: a retrospective study.

BACKGROUND: Toscana virus (TOSV) is an arthropod-borne virus transmitted by phlebotomine sandflies (Phlebotomus sp.) widespread throughout the Mediterranean having the potential to cause meningoencephalitis in humans. In Germany, the vectors of TOSV are introduced recently and become endemic especially in Southwestern Germany. As TOSV is not investigated regularly in patients with meningoencephalitis, cases of TOSV-neuroinvasive disease may remain mostly undetected. METHODS: We conducted a retrospective cohort study on patients with meningoencephalitis without identification of a causal pathogen from 2006 to 2016. Serologic assessment for anti-TOSV-IgG and IgM was performed on serum and CSF. Demographic, clinical and CSF data from TOSV-positive patients were compared to a cohort of patients with meningoencephalitis due to enterovirus. Informed consent was obtained from all included patients. RESULTS: We found 138 patients with meningoencephalitis without identified causal pathogen. From 98 of these patients CSF and serum was available for further testing. Additionally, we included 27 patients with meningoencephalitis due to enterovirus. We identified two patients with serological confirmed TOSV-neuroinvasive disease (TOSV-IgM and IgG positive, 2%) and two patients with possible TOSV-neuroinvasive disease (isolated TOSV-IgM positive, 2%). Overall, TOSV-neuroinvasive was detected in 4% of our cases with suspected viral meningoencephalitis. None of them had a history of recent travel to an endemic area. CONCLUSIONS: We found cases of TOSV-neuroinvasive disease in our German cohort of patients with meningoencephalitis. As no recent history of travel to an endemic area was reported, it remains probable that these cases resemble autochthonous infections, albeit we cannot draw conclusions regarding the origin of the respective vectors. TOSV could be considered in patients with meningoencephalitis in Germany.

Immunoblot reactivity at follow-up in treated patients with Lyme neuroborreliosis and healthy controls.

About 5-20% of the general population in endemic areas have seroprevalence for anti-borrelial antibodies. Previous studies have shown a high rate of 25-97% of persisting anti-borrelial antibodies in patients with treated Lyme neuroborreliosis (LNB) at follow-up. These studies used immunoblots with antigens from whole-cell sonicates, which could be less specific than modern recombinant antigens. We assessed the seroprevalence of anti-borrelial antibodies in serum from patients with definite LNB and healthy controls with a line immunoblot using highly specific recombinant antigens. We retrospectively identified patients with treated definite LNB who were treated at the Medical Center-University of Freiburg. Serum from LNB patients at a mean follow-up period of 4.9 years (SD: 3.3) and serum from healthy controls were assessed for anti-borrelial antibodies with a line immunoblot with recombinant antigens. A total of 45 patients with definite LNB and 40 healthy controls were included. Ten LNB patients (22.7%) had persisting antibodies (IgG and/or IgM) in serum at follow-up. Serum samples from six healthy controls (15%) were positive for anti-borrelial antibodies (IgG and or IgM). Prevalence of positive IgM or IgG antibodies showed no statistically significant difference between LNB patients at follow-up and healthy controls (IgM p = 0.32, IgG p = 0.54). Immunoblot reactivity patterns at follow-up in LNB patients did not have statistically significant differences from healthy controls. The discrepancy regarding earlier studies reporting higher amounts of LNB patients with persisting antibodies could be due to a higher specificity of the antigens used in recombinant immunoblots compared to other immunoblots (e.g., whole-cell sonicates). The results of our study should be replicated in a larger prospective multi-center study.

Erythrophages do not develop when lumbar CSF and blood samples are mixed in vitro.

BACKGROUND: Cerebrospinal fluid (CSF) analysis is a crucial method in the diagnostic process for suspected subarachnoid hemorrhage (SAH), especially when cerebral imaging is negative or inconclusive. CSF cytology (detection of erythrophages or siderophages) is used to determine whether a bloodstained CSF resembles a genuine SAH. Whether erythrophages may develop in vitro after a traumatic puncture in case of delayed CSF analysis is unclear. An in vitro development of erythrophages after traumatic puncture would diminish the diagnostic properties of CSF analysis. We assessed whether erythrophagocytosis is detectable in CSF after an imitated traumatic lumbar puncture. METHODS: We mimicked a traumatic lumbar puncture by mixing surplus CSF with whole blood from the same patient. From this mixture, cytological specimens were obtained immediately and repeatedly at time intervals of 1 h, until 7 h after mixing, or until the mixture was exhausted. Each cytological specimen was microscopically examined independently by four experienced CSF cytologists for the presence of erythrophages. RESULTS: We studied 401 CSF cytological specimens of 96 punctures in 90 patients. We could not identify any erythrophages in all cytological specimens. Fleiss' Kappa for interrater-reliability was 1.0. CONCLUSIONS: We did not find evidence for an in vitro erythrophagocytosis after a mimicked traumatic lumbar puncture. Therefore, the occurrence of erythrophages in CSF cytology can be regarded as a reliable sign of an autochthonous bleeding in the subarachnoid space. Our results support the crucial role of CSF analysis in clinical practice in case of a suspected SAH but negative cerebral imaging.

[Neuroborreliosis - Diagnostics, treatment and course]. / Neuroborreliose ­ Diagnostik, Therapie und Verlauf.

Lyme neuroborreliosis is a tick-borne infectious disease caused by the spirochete bacterium Borrelia burgdorferi sensu lato. Clinical manifestations are classified as early and late Lyme neuroborreliosis. Early manifestations are much more common than late manifestations. Serological testing should only be performed when typical neurological symptoms are present because false positive results are common due to a high seroprevalence in the population. Cerebrospinal fluid (CSF) analysis should be performed if Lyme neuroborreliosis is suspected. A systematic review found similar effects of beta-lactam antibiotics and doxycycline regarding the outcome of neurological symptoms and adverse effects. The prognosis after antibiotic treatment is usually favorable and residual symptoms can rarely persist. Impairments in quality of life, fatigue, depression and cognitive impairment are not more frequent in patients after treatment of Lyme neuroborreliosis than in the normal healthy population.

Prevalence and spectrum of residual symptoms in Lyme neuroborreliosis after pharmacological treatment: a systematic review.

Controversy exists about residual symptoms after pharmacological treatment of Lyme neuroborreliosis. Reports of disabling long-term sequels lead to concerns in patients and health care providers. We systematically reviewed the available evidence from studies reporting treatment of Lyme neuroborreliosis to assess the prevalence and spectrum of residual symptoms after treatment. A literature search was performed in three databases and three clinical trial registers to find eligible studies reporting on residual symptoms in patients after pharmacological treatment of LNB. Diagnosis must have been performed according to consensus-derived case definitions. No restrictions regarding study design or language were set. Symptom prevalence was pooled using a random-effects model. Forty-four eligible clinical trials and studies were found: 8 RCTs, 17 cohort studies, 2 case-control studies, and 17 case series. The follow-up period in the eligible studies ranged from 7 days to 20 years. The weighted mean proportion of residual symptoms was 28 % (95 % CI 23-34 %, n = 34 studies) for the latest reported time point. Prevalence of residual symptoms was statistically significantly higher in studies using the "possible" case definition (p = 0.0048). Cranial neuropathy, pain, paresis, cognitive disturbances, headache, and fatigue were statistically significantly lower in studies using the "probable/definite" case definition. LNB patients may experience residual symptoms after treatment with a prevalence of approximately 28 %. The prevalence and spectrum of residual symptoms differ according to the applied case definition. Symptoms like fatigue are not reported in studies using the "probable/definite" case definition. As the "possible" case definition is more unspecific, patients with other conditions may be included. Reports of debilitating fatigue and cognitive impairment after LNB, a "post-Lyme syndrome", could therefore be an artifact of unspecific case definitions in single studies.

Methodological quality of guidelines for management of Lyme neuroborreliosis.

BACKGROUND: Many aspects of clinical management of Lyme neuroborreliosis are subject to intense debates. Guidelines show considerable variability in their recommendations, leading to divergent treatment regimes. The most pronounced differences in recommendations exist between guidelines from scientific societies and from patient advocacy groups. Assessment of the methodological quality of these contradictory guideline recommendations can be helpful for healthcare professionals. METHODS: Systematic searches were conducted in MEDLINE and databases of four international and national guideline organizations for guidelines on Lyme neuroborreliosis published from 1999-2014. Characteristics (e.g., year of publication, sponsoring organization) and key recommendations were extracted from each guideline. Two independent reviewers assessed the methodological quality of each guideline according to the Appraisal of Guidelines for Research and Evaluation II (AGREE II) tool. AGREE II scores from guidelines developed by scientific societies and from patient advocacy groups were compared across domains. RESULTS: We identified eight eligible guidelines of which n = 6 were developed by scientific societies and n = 2 by patient advocacy groups. Agreement on AGREE II scores was good (Cohen's weighted kappa = 0.87, 95% CI 0.83-0.92). Three guidelines, all from scientific societies, had an overall quality score of ≥ 50%. Two of them were recommended for use according to the AGREE II criteria. Across all guidelines, the AGREE II domain with the highest scores was "Clarity of Presentation" (65, SD 19%); all other domains had scores < 50% with the domain "Applicability" having the lowest scores (4, SD 4%). Guidelines developed by scientific societies had statistically significantly higher scores regarding clarity of presentation than guidelines from patient advocacy groups (p = 0.0151). No statistically significant differences were found in other domains. CONCLUSIONS: Current guidelines on Lyme neuroborreliosis vary in methodological quality and content. Health care providers and patients need to be aware of this variability in quality when choosing recommendations for their treatment decisions regarding Lyme neuroborreliosis. No statement can be given on quality of content and validity of recommendations, as these issues are not subject to assessment with the AGREE II tool and are prone to individual interpretation of the available evidence by the corresponding guideline panels. To enhance guideline quality, guideline panels should put more emphasis on linking recommendations to the available evidence, transparency in reporting how evidence was searched for and evaluated, and the implementation of recommendations into clinical practice.

Efficacy and safety of pharmacological treatments for acute Lyme neuroborreliosis - a systematic review.

BACKGROUND AND PURPOSE: Our aim was to evaluate the available evidence for pharmacological treatment of acute Lyme neuroborreliosis as a basis for evidence-based clinical recommendations in a systematic review. METHODS: A systematic literature search of Medline, EMBASE, the Cochrane Library and three trial registries was performed. Randomized controlled trials (RCTs) and non-randomized studies (NRS) were evaluated. Risk of bias was assessed using the Cochrane risk of bias tools. The primary outcome was 'residual neurological symptoms' whilst the secondary outcomes were disability, quality of life, pain, fatigue, depression, cognition, sleep, adverse events and cerebrospinal fluid pleocytosis. The quality of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. RESULTS: After screening 5779 records, eight RCTs and eight NRS were included. Risk of bias was generally high. No statistically significant difference was found between doxycycline and beta-lactam antibiotics in a meta-analysis regarding residual neurological symptoms at 4-12 months [risk ratio (RR) 1.27, 95% confidence interval (CI) 0.98-1.63, P = 0.07] or adverse events (RR 0.82, 95% CI 0.54-1.25, P = 0.35). Significantly fewer neurological symptoms for cefotaxime compared with penicillin were found (RR 1.81, 95% CI 1.10-2.97, P = 0.02). Adverse events were significantly fewer for penicillin (RR 0.56, 95% CI 0.38-0.84, P = 0.005). CONCLUSIONS: Evidence regarding pharmacological treatment of acute Lyme neuroborreliosis is scarce and therefore insufficient to recommend preference of beta-lactam antibiotics over doxycycline or vice versa. However, due to considerable imprecision, relevant differences between treatments cannot be excluded. No evidence suggesting benefits of extended antibiotic treatments could be identified. Further well-designed trials are needed. Individual treatment decisions should address patients' preferences and individual conditions like prior allergic reactions.

The chemokine CXCL13 is elevated in the cerebrospinal fluid of patients with neurosyphilis.

BACKGROUND: The chemokine CXCL13 has been discussed as a diagnostic parameter with high specificity for Lyme neuroborreliosis (LNB) and as a marker of disease activity. Neurosyphilis and LNB share similar characteristics. We investigated retrospectively CXCL13 levels in the cerebrospinal fluid (CSF) of patients with neurosyphilis at initial diagnosis and during treatment. RESULTS: Five patients with neurosyphilis were identified retrospectively using an electronic database in a tertiary care hospital from 2005 to 2012. CXCL13 levels were measured using an ELISA. Five patients with definite LNB and 10 patients with multiple sclerosis (MS) served as controls. Median CXCL13 levels at baseline were 972 pg/mL for neurosyphilis patients, 8,000 pg/mL for LNB patients, and 7.8 pg/mL for MS patients. Patients with LNB and neurosyphilis showed significantly higher CXCL13 levels in their CSF compared to MS patients (p < 0.05, p < 0.001, respectively). CXCL13 levels in the CSF declined during treatment. CONCLUSION: CXCL13 levels in the CSF of patients with neurosyphilis can be as high as in patients with LNB, exceeding the proposed threshold of 250 pg/mL for the diagnosis of LNB. Patients with encephalitic/myelitic syndromes appear to have especially high levels of CXCL13. Clinicians should be aware that high levels of CXCL13 are not found exclusively in LNB but also in other infectious diseases of the CNS.

Partial status epilepticus after electroconvulsive therapy and medical treatment with bupropion.

Electroconvulsive therapy (ECT) is the most effective treatment for therapy-refractory depression. Usually, prior antidepressant medication will be continued during ECT. However, the seizure threshold may be influenced by psychotropic drugs. We report a patient who received right unilateral ECT under concomitant treatment with bupropion, a selective noradrenaline- and dopamine-reuptake inhibitor. After the fourth session, a focal status epilepticus occurred, which was pharmacoresistant for the duration of 12 days. We assume that the induction of a status may be facilitated by a lowering of the seizure threshold due to bupropion. An evaluation of drug therapy and control of EEG before and during ECT are recommended, especially when the drug treatment has an influence on the seizure threshold.

Organic nanofibers containing insect pheromone disruptants: a novel technical approach to controlled release dispensers with potential for process mechanization.

Beginning fifty years ago, the search for suitable dispensers containing insect pheromones grew with the availability of these synthetic biotechnical tools. Many economic entomologists and application engineers dearly wish they had the "smart, intelligent and ideal dispenser". More or less suitable approximations are available commercially, but none so far meets all demands. Under economic strictures, novel inexpensive systems would be advantageous with release characteristics tailored to the specific life histories of pest insects, the plants considered and the numerous requirements of growers alike. Simultaneously, their field distribution should be mechanizable and be accomplished by one (or very few) application runs. The dispensers should be biodegradable, biocompatible, sustainably applicable, and they should be based on renewable resources. This report presents first results of a novel organic, electrospun nanofiber dispenser with dimensions in the upper nanometer range. Its load of pheromone can be adjusted to be sufficient for 7 weeks of constant disruptive action in vineyards and can be directed against the European Grape Vine Moth Lobesia botrana (Lepidoptera: Tortricidae) which here serves as a readily available model. Mating disruption in L. botrana and the related Eupoecilia ambiguella is a well studied and developed engineering process. Equally, nanofiber production by electrospinning (for a comprehensive review see Greiner and Wendorff, 2007A, B) is well known and already has numerous applications in filtration technology, air conditioning, and medical wound dressing. Our goal was to bring together and successfully mate these (partly incompatible) technologies via technical tricks of a proprietary nature. Even though the lifetime and effectiveness of currently available nanofibers still must be doubled, the rather complicated system of their production and analysis is known well enough to identify the parameters that need future adjustment. Another challenge is the mechanical distribution of the fibers in the vineyards by suitable machinery. Also, in this respect, certain technical leads are available for future development.

Organic electrospun nanofibers as vehicles toward intelligent pheromone dispensers: characterization by laboratory investigations.

Organic nanofibers have a history of technical application in various independent fields, including medical technology, filtration technology, and applications of pharmaceuticals via inhalation into the lungs. Very recently, in a joint effort with polymer chemists, agricultural applications have been added to this list of priorities. The aim is finding novel approaches to insect control. Pheromones, dispensed in a quantifiable way, are being used here in disrupting the mating communication between male and female pest insects, e.g. the European grapevine moth Lobesia botrana (Lepidoptera: Tortricidae), where current dispenser technology does not fully meet the high expectations of growers and environmentalists with respect to longevity of constant release, self decomposition, mechanical distribution, renewability as well as sustainability of resources. The methodology of electrospinning is exhaustively covered by Greiner and Wendorff (2007), with technical details reported by Hellmann et al. (2009), Hein et al. (2011), and Hummel et al. (2010). Wind tunnel studies were run within a tunnel with adjustable laminar flow and 0.5 m/sec air velocity. Mass losses of the electrospun fiber bundles were determined with a sensitive analytical balance 2-3 times per week and recorded as time vs. mass change. CLSA experiments were performed with a self developed glass apparatus (Lindner, 2010) based on various suggestions of previous authors. Microgram quantities of volatile pheromone (E,Z)-7,9-Dodecadienylacetate were absorbed on a filter of rigorously purified charcoal and desorbed by repeated micro extraction with a suitable solvent mixture. Aliquots of the solution were subjected to temperature programmed capillary GLC. Retention times were used for identification, whereas the area covered by the pheromone peak originating from a FID detector signal was integrated and compared with a carefully calibrated standard peak. Since these signals were usually in the low nanogram range, several replications were averaged for statistical improvement. - Thermogravimetric analysis between ambient temperature and 500 degrees C provided a series of degradation curves where the diagram contained information on the evaporation of pheromone alone, polymer fiber alone and pheromone included in the fiber.- Microscopic investigations resulted in pictures of nanofibers from which the overall morphology and the fiber dimensions could be quantified. Organic nanofibers loaded with the grapevine moth pheromone have been well characterized by 5 different lab methods, followed by field bioassays reported elsewhere in these communications volumes (HUMMEL et al., 2011). This comprehensive analytical approach to fiber characterization is new and will be further refined. The federal agency JKI Berlin subjected the pheromone loaded organic fibers to various independent toxicological and ecotoxicological tests and found no adverse side effects.

Physical fitness in depressive patients and impact of illness course and disability.

BACKGROUND: There is a large and increasing body of evidence that physical exercise, such as endurance training, exerts antidepressant effects in psychiatric disorders. However, compliance rates are rather low due to reduced energy and lack of motivation. Another important reason may be low baseline fitness leading to overstrain when participating in a training program. The aim of the study was to evaluate the physical fitness of depressive patients compared to healthy controls by a standardized assessment. METHODS: 51 hospitalized depressive patients were investigated by a standardized physical fitness assessment on a bicycle ergometer including measurement of maximum workload (pmax), heart rate, lactate concentration, workload at first lactate elevation (pLT), individual anaerobic threshold (IAT) and workload at IAT (pIAT). They were compared to 51 healthy controls matched for age, sex and body mass index. RESULTS: p(max), p(LT) and p(IAT) were markedly reduced in depressive patients compared to healthy controls (p<0.001). Lactate increase was faster and steeper in depressed patients, albeit differences never reached significant levels. There was a significant negative correlation between the length of disability and poor performance parameters but no significant correlation with other illness variables. LIMITATIONS: The study was not prospective and no study protocol was applied. CONCLUSION: This study demonstrates a marked reduction of physical fitness in depressive patients which cannot be explained by differences of body mass index or age. When designing therapeutic exercise programs for depressive patients evaluation of baseline training level is recommendable because many patients might overstrain themselves because of strongly reduced baseline fitness.

Intercomparison of methods for coincidence summing corrections in gamma-ray spectrometry.

A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing correction factors for several energies of (152)Eu and (134)Cs, and three source-to-detector distances. They are presented and discussed.

Alpha-particle emission probabilities in the decay of 240Pu.

Sources of enriched (240)Pu were prepared by vacuum evaporation on quartz substrates. High-resolution alpha-particle spectrometry of (240)Pu was performed with high statistical accuracy using silicon detectors and with low statistical accuracy using a bolometer. The alpha-particle emission probabilities of six transitions were derived from the spectra and compared with literature values. Additionally, some alpha-particle emission probabilities were derived from gamma-ray intensity measurements with a high-purity germanium detector. The alpha-particle emission probabilities of the three main transitions at 5168.1, 5123.6 and 5021.2 keV were derived from seven aggregate spectra analysed with five different fit functions and the results were compatible with evaluated data. Two additional weak peaks at 4863.5 and 4492.0 keV were fitted separately, using the exponential of a polynomial function to represent the underlying tailing of the larger peaks. The peak at 4655 keV could not be detected by alpha-particle spectrometry, while gamma-ray spectrometry confirms that its intensity is much lower than expected from literature.

[Erythropoietin protects retinal ganglion cells and visual function after ocular ischemia and optic nerve compression]. / Erythropoietin schützt retinale Ganglienzellen und die Sehfunktion nach Ischämie und Sehnervkompression im Rattenmodell.

BACKGROUND: The glycoprotein erythropoietin (EPO) has been shown to be protective in models of neuronal disease and reduced apoptosis of retinal ganglion cells (RGC) after transection of the optic nerve and in glaucoma. In this study we assessed in vivo the properties of EPO on survival of RGC after ischemia and optic nerve compression, as well as on postischemic visual function. Furthermore, the safety of intravitreal injection was assessed. METHODS: In all experiments, EPO was administered intravitreally in male Brown Norway rats. Ocular ischemia was induced by elevating the intraocular pressure for 55 min. The calibrated optic nerve compression was performed for 10 s. RGC were marked stereotactically and quantified by fluorescence microscopy. The retinal function was quantified by electroretinography (ERG) and the whole visual pathway by visual evoked potential (VEP). RESULTS: EPO (2 and 20 units per eye, n=9-21) increased the survival of RGC after ischemia by 21+/-21% and 127+/-31% (mean +/- SEM) and after optic nerve compression by 28+/-12% and 58+/-13%. With EPO (20 units), postischemic function was increased, in ERG by 71+/-13% (a-wave) and 75+/-19% (b-wave) and in VEP by 264+/-65% (p=0.053). Neither the ERG parameters, nor the VEP, nor the number of RGC differed significantly after intravitreal injection of EPO (5, 50, and 200 units, n=6-7) in healthy eyes. CONCLUSION: The combination of toxicological safety and protection of retinal neurons makes EPO a promising drug for ischemic retinal diseases and traumatic optic neuropathy.

Lack of obvious influence of PLLA nanofibers on the gene expression of BMP-2 and VEGF during growth and differentiation of human mesenchymal stem cells.

Growth factors like bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF) play an important role in bone remodeling and fracture repair. Therefore, with respect to tissue engineering, an artificial graft should have no negative impact on the expression of these factors. In this context, the aim of this study was to analyze the impact of poly(L-lactic acid) (PLLA) nanofibers on VEGF and BMP-2 gene expression during the time course of human mesenchymal stem cell (hMSC) differentiation towards osteoblasts. PLLA matrices were seeded with hMSCs and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of VEGF and BMP-2. Furthermore, BMP-2-enwoven PLLA nanofibers were used in order to elucidate whether initial down-regulation of growth factor expression could be compensated. Although there was a great interpatient variability with respect to the expression of VEGF and BMP-2, PLLA nanofibers tend to result in a down-regulation in BMP-2 expression during the early phase of cultivation. This effect was diminished in the case of VEGF gene expression. The initial down-regulation was overcome when BMP-2 was directly incorporated into the PLLA nanofibers by electrospinning. Furthermore, the incorporation of BMP-2 into the PLLA nanofibers resulted in an increase in VEGF gene expression. Summarized, the results indicate that the PLLA nanofibers have little effect on growth factor production. An enhancement in gene expression of BMP-2 and VEGF can be achieved by an incorporation of BMP-2 into the PLLA nanofibers.

One-step production of polymeric microtubes by co-electrospinning.

Herein we demonstrate the ability to fabricate polymeric microtubes with an inner diameter of approximately 3 microm through co-electrospinning of core and shell polymeric solutions. The mechanism by which the core/shell structure is transformed into hollow fibers (microtubes) is primarily based on the evaporation of the core solution through the shell and is described here in detail. Additionally, we present the filling of these microtubes, thus demonstrating their possible use in microfluidics. We also report the incorporation of a protein (green fluorescent protein) within such fibers, which is of interest for sensorics.

[Electrospun poly-l-lactide nanofibres as scaffolds for tissue engineering]. / Elektrogesponnene Poly-L-Laktid-Nanofasern als resorbierbare Matrix für Tissue-Engineering.

Tissue engineering is a promising tool for treating structural and functional defects in bone and cartilage. To provide optimal conditions for three-dimensional cell growth the use of a scaffold is necessary. The aim of the study was to test the potential application of an electrospun poly (l-lactide)-nanostructured scaffold as a matrix for tissue engineering. Matrices were seeded with human osteosarcoma MG-63 cells and cultivated for 14 days. Cells showed a clear preference for growth along the nanofibres, and demonstrated no signs of degeneration or apoptosis. The fine structure of electrospun nanofibres makes them an ideal scaffold for tissue engineering, in particular for cartilage repair. They can be "doped" with growth factors, medications, etc., and are both biocompatible and biodegradable.

Primary and secondary measurements of 222Rn.

In the past few years, a primary measurement system has been established at the PTB allowing absolute measurements of 222Rn. The activity can be determined by counting the emitted alpha particles in a defined solid angle after condensing the radon at a cold point under vacuum conditions. This primary measurement system is connected to a solid 226Ra source, where 222Rn can be produced up to an activity of about 2MBq. After the measurement, radon can be completely transferred into a glass bulb or a stainless steel cylinder for use as a transfer standard. The results of the measurements, the uncertainties and the realization of the primary measurement system are described. For quality assurance and fast determination of radon activity, a secondary measurement system with an NaI(Tl) detector is also used. Together, both systems provide a reliable tool for the production of gaseous 222Rn activity standards with relative uncertainties of less than 1%.