[MRT follow-up study of spontaneous regression of lumbar articular facet cyst].
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Female↗
Biomedical subjects
M Scholz
Publications and source records attributed to M Scholz.
Consideration of ergonomic aspects in the development of a new endoscopic navigation system.
During the development of new navigation systems, the ergonomic aspects of the accompanying software are seldom taken into account. The VN system is a navigation system working with real and previously stored neuroendoscopic images. The latter enable the module to execute virtual back movement, e.g. in case of bleeding. Several other modules are offered. The aim of the study was the ergonomic analysis of different modules and their learning curves in cadaveric heads. The endoscope was navigated by the neurosurgeon while another person operated the computer. A total of 128 experiments were performed with two software versions. When the landmark tracking module was used, a real learning curve could be observed. By contrast, testing the measurement module did not produce a learning curve. A significant reduction of the time required by the three modules investigated could be observed with software version 2. The module for virtual back movement works best with a minimum time of 20 s for image storage. During machine-human interactions ergonomic software use is important, especially if operative procedures are performed.
Clinical Competence↗
Correlation between mitotic delay and aberration burden, and their role for the analysis of chromosomal damage.
The aim was to investigate further the relationship between radiation-induced mitotic delay and the expression of chromosome damage in V79 cells. Recently published data on the time-course of chromosome aberrations in V79 first-cycle metaphases after exposure to 10.4 MeV u(-1) Ar ions (LET = 1226 keV microm(-1)) were supplemented and reanalysed. A statistical analysis of the distribution of aberrations among cells was performed. Furthermore, cells were grouped into subpopulations carrying 0, 1 -2, 3-4, 5- 6 and 7 or more aberrations. Then, based on the mitotic index, the flux of each subgroup through the first mitosis was determined and the average entrance time to mitosis was estimated. For comparison, the flux of aberrant V79 cells generated by X-irradiation was analysed. Analysis of the Ar ion data revealed that the flux of each subpopulation through the first mitosis is strongly affected by its aberration burden, i.e. a positive correlation between the mitotic delay and the number of aberrations carried by a cell was observed. The distribution of aberrations among cells could be well described by Neyman-type A statistics; the corresponding fit parameters also reflect the damage-dependent mitotic delay. Interestingly, comparison of the flux of Ar ion and X-ray-irradiated V79 cells through mitosis revealed (1) that a direct correlation exists between the number of aberrations carried by a cell and its average entrance time to mitosis, and (2) that this effect is independent of the linear energy transfer. The role of these observations for radiation cytogenetics is discussed.
Animals↗
Treatment of gully pot liquor containing heavy metals with constructed wetlands in Scotland.
The aim of this investigation was to assess the treatment efficiencies for gully pot liquor of 12 experimental vertical-flow constructed wetland filters containing Phragmites australis (Cav.) Trin. ex Steud. (Common Reed) and filter media of different adsorption capacities in a cold climate. Seven of the twelve filters received inflow water spiked with heavy metals. For one year, hydrated copper nitrate and hydrated nickel nitrate were added to sieved gully pot liquor to simulate contaminated primary treated storm water runoff. The inflow concentrations for dissolved copper, nickel and nitrate-nitrogen were approximately 1.0, 1.0 and 1.45 mg/l, respectively, which represent mean loading rates of 0.063 g/m2/d for Filters 2 and 7 to 11, and 0.115 g/m2/d for Filter 12. For these filters receiving metals, an obvious breakthrough of dissolved nickel was recorded after road gritting and salting during winter. Sodium chloride was responsible for nickel leaching. Reductions of copper, nickel, biochemical oxygen demand and suspended solids were frequently insufficient compared to international secondary wastewater treatment standards. Moreover, the overall filtration performance for all filters was similar.
Climate↗
Modelling human granulopoiesis under poly-chemotherapy with G-CSF support.
Cytotoxic drugs administered in polychemotherapy cause a characteristic neutropenic period depending on the schedule of the drugs, which can partly be prevented by G-CSF growth factor support. To quantify these effects and to gain a deeper insight into the dynamics of bone marrow recovery after such suppressing and stimulating disturbances, we construct a biomathematical compartment model of human granulopoiesis under polychemotherapy with G-CSF support. The underlying assumptions and mathematical techniques used to obtain the model are explained in detail. A large variety of biological and clinical data as well as knowledge from a model of murine haematopoiesis are evaluated to construct a physiological model for humans. Particular emphasis is placed on estimating the influence of chemotherapeutic drugs on the granulopoietic system. As a result, we present an innovative method to estimate the bone marrow damage caused by cytotoxic drugs with respect to single identifiable cell stages only on the basis of measured peripheral blood leukocyte dynamics. Conversely, our model can be used in a planning phase of a clinical trial to estimate the haematotoxicity of regimens based on new combinations of drugs already considered and with or without growth factor support.
Animals↗
Metabolite fingerprinting: detecting biological features by independent component analysis.
MOTIVATION: Metabolite fingerprinting is a technology for providing information from spectra of total compositions of metabolites. Here, spectra acquisitions by microchip-based nanoflow-direct-infusion QTOF mass spectrometry, a simple and high throughput technique, is tested for its informative power. As a simple test case we are using Arabidopsis thaliana crosses. The question is how metabolite fingerprinting reflects the biological background. In many applications the classical principal component analysis (PCA) is used for detecting relevant information. Here a modern alternative is introduced-the independent component analysis (ICA). Due to its independence condition, ICA is more suitable for our questions than PCA. However, ICA has not been developed for a small number of high-dimensional samples, therefore a strategy is needed to overcome this limitation. RESULTS: To apply ICA successfully it is essential first to reduce the high dimension of the dataset, by using PCA. The number of principal components determines the quality of ICA significantly, therefore we propose a criterion for estimating the optimal dimension automatically. The kurtosis measure is used to order the extracted components to our interest. Applied to our A. thaliana data, ICA detects three relevant factors, two biological and one technical, and clearly outperforms the PCA.
Algorithms↗
Use of NT-proBNP in routine testing and comparison to BNP.
OBJECTIVES: B-type natriuretic peptide (BNP) is a strong diagnostic predictor of left-ventricular (LV)-dysfunction. Recently, the aminoterminal portion of pro-BNP (NT-proBNP) has been introduced, which could be even more sensitive because of its longer half-life. The aim of this study was to evaluate the new marker NT-proBNP within a large, heterogeneous population of patients with suspected cardiovascular disease at risk of cardiovascular dysfunction and to compare it with the established diagnostic parameter BNP. SUBJECTS AND METHODS: NT-proBNP and BNP were measured in 339 hospitalised patients undergoing diagnostic angiography (median age 66 years, 244 male vs. 95 female). RESULTS: Median values of NT-proBNP increased with worsening LV-dysfunction and higher NYHA class. The area under the receiver operator characteristics curve (AUC) of NT-proBNP for detecting severe systolic dysfunction or for detecting any systolic LV-dysfunction was 0.83 and 0.77, respectively. The latter improved (AUC=0.81) when patients with clinically relevant heart disease like valvular dysfunction were included, independent of the haemodynamic values. Compared to BNP, NT-proBNP tended to be more accurate in identifying lesser degrees of LV-dysfunction. CONCLUSIONS: Even after optimisation of target criteria, there was still a substantial overlap of NT-proBNP values between patients with and without relevant heart disease. Therefore, NT-proBNP is not suitable as a screening test for LV-dysfunction in the community. Nevertheless, because of its good negative predictive value, NT-proBNP could be an easy and effective tool to rule out severe systolic LV-dysfunction in high risk patients. No clinically significant advantage of BNP testing could be found.
Aged↗
[Biodegradable cage. Osteointegration in spondylodesis of the sheep cervical spine].
Bioabsorbable implants are commonplace in knee and shoulder surgery. Bioabsorbable poly(l-lactide-co-D,L-lactide) (PLDLLA) cage devices have potential benefits over autologous tricortical iliac crest bone graft and metallic cages for cervical spine interbody fusion. The purpose of this study was to compare interbody fusion of an autologous tricortical iliac crest bone graft with that of a bioabsorbable cage using a sheep cervical spine interbody fusion model. This study was designed to determine differences in (1) the ability to preserve postoperative distraction, (2) biomechanical stability, and (3) histological characteristics of intervertebral bone matrix formation. Sixteen full-grown Merino sheep underwent C3/4 discectomy and fusion. After 12 weeks, there was no significant difference between the results with the bioabsorbable PLDLLA cages and tricortical bone grafts. The cage also did not show advanced interbody fusion but did, however, show large osteolysis, which allows skepticism regarding the value of this bioabsorbable implant.
Absorbable Implants↗
Treatment planning for scanned ion beams.
Since 1997 a radiotherapy unit using fast carbon ions is operational at GSI. An intensity-controlled magnetic raster scanner together with a synchrotron allowing fast energy variation enable a unique method of purely active dose shaping in three dimensions. This contribution describes the necessary steps to establish a treatment planning system for this novel modality. We discuss the requirements for the physical beam model and the radiobiological model. Based on these we chose to implement a home-grown pencil beam model to describe the ion-tissue interaction and the Local Effect Model to calculate the RBE voxel-by-voxel. Given the large number of degrees of freedom biological dose optimization must be achieved by means of inverse treatment planning. All ion-related aspects are collected in our TRiP98 software. Biological dosimetry measuring cell survival in two dimensions turns out to be a good way to verify the model predictions as well as the actual irradiation procedure. We show a patient example and outline the future steps towards a dedicated clinic facility for all light ions.
Carbon↗
Vibrography: first experimental results in swine brains.
OBJECT: The aim of this study was to determine whether vibrography, an ultrasound-based real-time strain imaging method for registering the elastic properties of tissue, is superior to conventional ultrasound imaging techniques for detecting low-contrast space-occupying lesions in brain tissue and for delineating the boundaries between such lesions and the surrounding tissue. METHODS: As our experimental model we used swine brains taken from freshly slaughtered pigs. After injecting agarose into these brains at different depths, we compared both the conventional ultrasonographic images and the elastographic images of the region of interest with the corresponding anatomical brain sections. RESULTS: In 83.6 % of the experiments, it was possible to detect the polymerized agarose in the brain tissue with vibrographic techniques. In 17 experiments agarose lesions which were not detectable by ultrasound were visualized via vibrography. Furthermore, statistical analysis revealed that elastography is a more precise tool than conventional ultrasound for determining lesion size. CONCLUSION: These findings indicate that vibrography is a promising real-time imaging method with numerous potential applications in the field of neurosurgery. Visualization of the elastic properties provides the neurosurgeon with additional data on the lesion and the boundary between the lesion and the surrounding tissue.
Animals↗
Induction of reproductive cell death and chromosome aberrations in radioresistant tumour cells by carbon ions.
PURPOSE: To study the induction of reproductive cell death and chromosome aberrations in radioresistant tumour cells exposed to carbon ions in vitro. MATERIALS AND METHODS: X-ray-resistant colon carcinoma cells (WiDr) were used. Confluent G0/G1 cells were irradiated in vitro with graded doses of 100/200/400 MeV u(-1) carbon ions and carbon ions from the middle of a 1 cm extended Bragg peak, and 200 kV X-rays for comparison. Cells were harvested in their first post-irradiation division and aberrations were analysed either by the Giemsa/Hoechst 33258-staining technique or by the fluorescent in-situ hybridization technique involving whole chromosome hybridization and 4',6-diaminido-2-phenylidole (DAPI)-staining. Whole chromosome probes were used for chromosomes 2, 4 and 5, and the chromosome painting patterns were classified according published protocols. Reproductive cell survival was determined by a standard clonogenic assay. RESULTS: With respect to the induction of reproductive cell death and chromosome aberrations, carbon ions of different energies were more effective than 200 kV X-rays. As expected, irradiation in the extended Bragg peak was the most efficient mode. For cell killing, relative biological effectiveness increased with linear energy transfer up to 2.9. The frequencies of total dicentrics and excess acentric fragments as determined in Giemsa-stained cells were higher in cells irradiated with carbon ions than in cells with X-rays. For 100 MeV u(-1) ions, the dose dependence of apparently simple dicentrics as determined for chromosomes 2, 4 and 5 by single-colour fluorescent in-situ hybridization was linear up to 4 Gy, and linear-quadratic for excess acentric fragments and apparently simple translocations. After irradiation with D=4 Gy carbon ions with energy of 100 MeV u(-1) and from the extended Bragg peak, 12 and 54% of cells displayed complex exchanges, respectively. In contrast, after irradiation with D=4 Gy X-rays, only 1% of cells displayed complex aberrations. Hence, the number of cells with complex exchange aberrations increased strongly after irradiation with carbon ions. CONCLUSION: An increased biological efficiency of carbon ions could be confirmed in radioresistant tumour cells with respect to the induction of reproductive cell death and of unstable as well as stable chromosome aberrations. Relative biological effectiveness reached 2.9 for cell killing by carbon ions from the extended Bragg peak. The yields of apparently simple dicentrics as well as of total dicentrics, i.e. simple dicentrics plus dicentrics belonging to complex exchanges, evaluated in Giemsa-stained metaphases as observed in first post-irradiation mitoses were rather low. In contrast, apparently simple translocations displayed yields systematically higher than simple dicentrics in WiDr cells irradiated with either X-rays or 100 MeV u(-1) or Bragg peak carbon ions. Frequencies o f cells containing complex aberrations increased dramatically after carbon ion irradiation, reaching a maximum for ions from the extended Bragg peak.
Carbon↗
Inhibition of neutrophil activity in cardiac surgery with cardiopulmonary bypass: a novel strategy with the leukocyte inhibition module.
Recently, we showed that the arterial in-line application of the leukocyte inhibition module (LIM) within the heart-lung machine limits overshooting leukocyte activity and cardiac tissue damage. Moreover, significantly better cardiac function was found in an experimental animal model when LIM was used. In the meantime, the first promising clinical data exist. LIM has to be regarded as an essential tool in extracorporeal circulation, in the future, to improve postoperative clinical outcome and to reduce costs. This review summarizes the biological background of LIM and the current experience obtained in experimental models and clinical studies.
Animals↗
Response of Chinese hamster v79 multicellular spheroids exposed to high-energy carbon ions.
Chinese hamster V79-379A spheroids 200 +/- 30 microm (+/- SD) in diameter were irradiated in agitated medium in different oxygen atmospheres with (1) 227 MeV/nucleon (12)C(+6) ions (plateau region) to model tissue in the entrance channel during therapy, (2) carbon ions in the extended Bragg peak modeling tissue in the target volume, or (3) X rays as a reference modality. Cell survival curves were similar for modes (1) and (3), indicating the absence of a contact effect and the presence of a pronounced oxygen effect with oxygen enhancement ratios (OERs) of 2.8 and 2.9, respectively. In contrast, the oxygen effect was substantially smaller in mode (2) with an OER of 1.4. Under normal or restricted oxygen supply conditions (external pO(2) = 145 or 0 mmHg), the relative biological effectiveness (RBE) was 2.1 or 4.3, respectively, for Bragg-peak irradiation. This modality induced apoptosis and a dose-dependent accumulation of cells in G(2)/M phase even at pO(2) = 0 mmHg. The volume ratios of treated to untreated spheroids exhibited cyclic variations after heavy-particle treatment that were not directly attributable to cell cycle synchronization. In summary, the results suggest that carbon ions in the extended Bragg peak are more effective than conventional X rays, particularly under hypoxic conditions.
Animals↗
The physical and radiobiological basis of the local effect model: a response to the commentary by R. Katz.
The physical and biological basis of our model to calculate the biological effects of charged particles, termed the local effect model (LEM), has recently been questioned in a commentary by R. Katz. Major objections were related to the definition of the target size and the use of the term cross section. Here we show that the objections raised against our approach are unjustified and are largely based on serious misunderstandings of the conceptual basis of the local effect model. Furthermore, we show that the approach developed by Katz and coworkers itself suffers from exactly those deficiencies for which Katz criticizes our model. The essential conceptual differences between the two models are discussed by means of some illustrative examples, based on a comparison with experimental data. For these examples, the predictions of the local effect model are fully consistent with the experimental data. In contrast, e.g. for very heavy ions, there are significant discrepancies observed for the Katz approach. These discrepancies can be attributed to the inadequate definition of the target size in this model. Experimental data are thus clearly in favor of the definition of the target as used in the local effect model. Agreement with experimental data is achieved for protons within the Katz approach but at the cost of questionable approximations in combination with the violation of the fundamental physical principle of energy conservation.
Animals↗
A track structure model for simulation of strand breaks in plasmid DNA after heavy ion irradiation.
We present a track structure model based on the local dose deposited around heavy ion tracks to explain the cross sections for single-strand and double-strand break induction in plasmid DNA in different aqueous buffers. The model is based only on measurable quantities, namely the effect distribution for inducing strand breaks after x-ray irradiation as a function of dose, and the radial dose distribution of the heavy ion track. The effect of indirect DNA damage mediated by free radicals produced in the water surrounding the DNA is accounted for by allowing the radial dose distribution to be smeared in space by an effective target size corresponding to the squared sum of the geometrical extension of the plasmid molecule and the mean free drift path of the radicals in the buffer solution. Our calculations reproduce well the measured cross sections for single-strand and double-strand break induction in SV40 plasmid DNA in various buffer solutions both as a function of the LET and of the specific energy of the heavy ion.
Buffers↗
Perioperative elastase activity in cardiac surgery and its role in endothelial leakage.
OBJECTIVE AND DESIGN: The functional activity and pathophysiological effects of polymorphonuclear elastase (PMNE) in cardiac surgery patients are unknown. This in vitro study was done to evaluate whether PMNE activity in patient blood samples may be correlated with decreased endothelial wall integrity. METHODS AND SUBJECTS: PMNE was serially analyzed by PMNE activity in plasma samples from 40 high risk cardiac surgery patients. Endothelial cell cultures were used to study the influence of patient serum on the intercellular integrity. RESULTS: Ex vivo, samples with high PMNE activity (>1.0 mg/ ml), found in 14 patients (35%), neither induced hyperpermeability in cultured endothelial cells nor resulted in intracellular redistribution of the junction molecules cadherin-5 or beta-catenin. However, pretreatment of endothelial cells with these samples but not with low activity (<0.5 mg/ml) samples augmented neutrophil transendothelial migration (>20-fold) in conjunction with formation of intercellular gaps and irregular membrane-associated beta-catenin staining. Neutrophil transmigration was inhibited by blocking neutrophil beta1 integrin but not by the proteinase inhibitor methoxysuccinyl-Ala-Ala-Pro-Ala. CONCLUSIONS: Augmented PMNE activity in cardiac surgery patients does not directly induce endothelial leakage but may indirectly promote neutrophil extravasation and thus perioperative endothelial hyperpermeability.
Blood-Air Barrier↗
A multivariate, spatiotemporal analysis of electromagnetic time-frequency data of recognition memory.
Electromagnetic indices of "fast" (above 12 Hz) oscillating brain activity are much more likely to be considerably attenuated by time-averaging across multiple trials than "slow" (below 12 Hz) oscillating brain activity. To the extent that both types of oscillations represent the activity of temporally and topographically separable neural populations, time averaging can cause a loss of brain activity information that is important both conceptually and for multimodal integration with hemodynamic techniques. To address this issue for recognition memory, simultaneous electroencephalography (EEG) and whole-head magnetoencephalography (MEG) recordings of explicit word recognition from 11 healthy subjects were analyzed in two different ways. First, the time course of neural oscillations ranging from theta (4.5 Hz) to gamma (42 Hz) frequencies were identified using single-trial continuous wavelet transforms. Second, traditional analyses of amplitude variations of time-averaged EEG and MEG signals, event-related potentials (ERPs), and fields (ERFs) were performed and submitted to distributed source analyses. To identify data patterns that covaried with the difference between correctly recognized studied (old) words and correctly rejected nonstudied (new) words, a multivariate statistical tool, partial least squares (PLS), was applied to both types of analyses. The results show that ERPs and ERFs are mainly displaying those neural indices of recognition memory that oscillate in the theta (4.5-7.5 Hz), alpha (8-11.5), and to some extent in the beta1 (12-19.5 Hz) frequency range. The sources of the ERPs/ERFs were in good agreement with the topography of theta/alpha/beta 1 oscillations in being confined to the anterior temporal lobe at 400 ms and being distributed across temporal, parietal, and occipital areas between 500 and 700 ms. Gamma oscillations covaried either positively or negatively with theta/alpha/beta1 oscillations. A positive covariance, for instance, was detected over left anterior temporal sensors as early as 200-350 ms and is compatible with studies in rodents showing that gamma and theta oscillations emerge together out of the interaction of the hippocampus and the entorhinal and perirhinal cortices. Fast beta oscillations (20-29.5 Hz), on the other hand, did not strongly covary with slow oscillations and were likely to arise from neural populations not adequately represented in ERPs/ERFs. In summary, by providing a more comprehensive description of electromagnetic signals, time-frequency data are of potential benefit for integrating electrophysiological and hemodynamic indices of brain activity and also for integrating human and animal electrophysiology.
Adolescent↗
Investigation of the pharmaceutical and pharmacological equivalence of different Hawthorn extracts.
Seven Hawthorn extracts were tested in isolated guinea pig aorta rings. The effect on noradrenaline- (10 microM) induced contraction was investigated. The extracts were prepared using ethanol (40 to 70% v/v), methanol (40 to 70% v/v), and water as the extraction solvents. The aqueous-alcoholic extracts displayed similar spectra of constituents. They were characterised by similar procyanidin, flavonoid, total vitexin and total phenols content and by similar TLC fingerprint chromatograms. The aqueous extract, however, showed a different fingerprint and a noticeably lower concentration of procyanidins, flavonoids and total phenols but a similar total vitexin content. All 7 extracts had a relaxant effect on the aorta precontracted by noradrenaline and led to relaxations to 44 until 29% of the initial values. The EC50 values of the aqueous-alcoholic extracts varied between 4.16 and 9.8 mg/l. The aqueous extract produced a similarly strong maximal relaxation as the other extracts, but the EC50, at 22.39 mg/l, was markedly higher. The results show that Hawthorn extracts with comparable quality profiles were obtained by using aqueous-alcoholic extraction solvents (40 to 70% ethanol or methanol). The extracts exerted comparable pharmacological effects. When using water as the extraction solvent, both, the spectrum of constituents and the pharmacological effect, deviated remarkably. It is thus possible to obtain bioequivalent extracts with comparable effect profiles by using 40 to 70% ethanol or methanol as the extraction solvent.
Animals↗