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S Vogt

Publications and source records attributed to S Vogt.

At least 19 recordsLinked to original sources
PubMed2006

Nanometer linear focusing of hard x rays by a multilayer Laue lens.

We report on a type of linear zone plate for nanometer-scale focusing of hard x rays, a multilayer Laue lens (MLL), produced by sectioning a multilayer and illuminating it in Laue diffraction geometry. Because of its large optical depth, a MLL spans the diffraction regimes applicable to a thin Fresnel zone plate and a crystal. Coupled wave theory calculations indicate that focusing to 5 nm or smaller with high efficiency should be possible. Partial MLL structures with outermost zone widths as small as 10 nm have been fabricated and tested with 19.5 keV synchrotron radiation. Focal sizes as small as 30 nm with efficiencies up to 44% are measured.

Journal Article↗
PubMed2006

Inhibition of carotis venous bypass graft disease by intraoperative nucleic acid-based therapy in rabbits.

BACKGROUND: Bypass graft stenosis after venous revascularisation procedures is characterised by massive neointimal and vascular smooth muscle cell proliferation triggered via endothelin-1 synthesis in the vessel wall. Decoy oligodesoxynucleotides (ODN) against the transcription factor activator protein-1 (AP-1) inhibits pre-pro-endothelin-1 expression. METHODS: In 20 rabbits, an end-to-side jugular vein bypass to the carotid artery was performed: (group A) 8 grafts were treated with consensus AP-1 decoy ODN, (group B) 8 with mutated control ODN and (group C) 4 received no treatment. Explantation, histomorphometric and immunohistochemical evaluation was performed after 28 days. RESULTS: Median intimal thickness of groups: (A) 28.3 microm, (B) 48.4 microm, (C) 71.1 microm. The decoy ODN-treated group showed a significant reduction of neointima formation ( P = 0.029) and a downregulation of the endothelin receptor. CONCLUSIONS: In this model, neointima formation was reduced by local transfection with consensus decoy ODN against AP-1. Endothelin A and B receptor expression is downregulated. Molecular target nucleic acid-based therapies seem to be a future means of overcoming neointima proliferation in pressure-induced venous graft failure. Intraoperative local application makes it easy to use in routine revascularisation procedures.

Animals↗
PubMed2006

Investigations on the association of D-lactate blood concentrations with the outcome of therapy of acidosis, and with posture and demeanour in young calves with diarrhoea.

The objective of this prospective study was to elucidate whether amounts of bicarbonate needed for correction of acidosis and normalization of clinical signs are influenced by blood D-lactate concentrations in calves with diarrhoea. In 73 calves up to 3 weeks old with acute diarrhoea and base excess values below -10 mmol/l correction of acidosis was carried out within 3.5-h by intravenous administration of an amount of sodium bicarbonate which was calculated using the formula: HCO (mmol) = body mass (kg) x base deficit (mmol/l) x 0.6 (l/kg). Clinical signs, venous base excess, and plasma D-lactate concentrations were monitored immediately following admission, following correction of acidosis at 4 h and 24 h after admission. The base excess and plasma D-lactate concentrations throughout the study were -17.8 +/- 4.0, -0.4 +/- 0.4, -3.0 +/- 5.5 mmol/l (base excess), and 10.0 +/- 4.9, 9.8 +/- 4.8, 5.4 +/- 3.4 mmol/l (D-lactate) for the three times of examination. Metabolic acidosis was not corrected in more than half of the calves (n = 43) by the calculated amount of bicarbonate, whereas the risk of failure to correct acidosis increases with D-lactate concentrations. The study shows that calves with elevated D-lactate concentrations do not need additional specific therapy, as D-lactate concentrations regularly fall following correction of acidosis and restitution of body fluid volume, for reasons that remain unclear. However, calves with distinct changes in posture and demeanour need higher doses of bicarbonate than calculated with the factor of 0.6 in the formula mentioned above probably because of D-hyperlactataemia.

Acid-Base Equilibrium↗
PubMed2005

Energy intake and energy expenditure of elite cyclists during preseason training.

In the last years, the interest in sport nutrition has increased. The purpose of this study was to quantify the nutritional status of eleven cyclists of a professional team (age: 28.7+/-4.2 yr; height: 181.0+/-4.2 cm; weight: 71.0+/-5.2 kg; body fat: 10.2+/-2.4%), during basic pre-season training. The athletes trained on five days (160 km per day) and respected one rest-day (33 km). The food of the cyclists, which was chosen by the riders themselves, was weighed and recorded for six days, the protocols were analysed through the PRODI 4.3 EXPERT database. The daily energy intake which averaged 13.5 MJ (59% carbohydrates, 19% proteins, and 21% fat), was compared to the mean daily consumption of energy (19.1 MJ), which was calculated from the basal metabolic rate and the energy turnover while training (directly measured through the SRM Training system). The daily energy expenditure was 30% higher than the daily energy intake. The analysis of the food diary showed that these experienced riders composed a carbohydrate-rich and low-fat diet by themselves as recommended for high-performance endurance athletes. When compared to nutritional guidelines, the composition of the diet in the present study can be considered as adequate.

Adult↗
PubMed2005

[The effect of sports activities in children and adolescents on the calcaneus--an investigation with quantitative ultrasound].

PURPOSE: To determine whether quantitative ultrasound (QUS) parameters speed of sound (SOS) and broadband ultrasound attenuation (BUA) on the calcaneus are different between athletic children and a reference population. PATIENTS AND METHODS: From a college of physical education, 177 children and adolescents (121 boys and 56 girls, age range from 11 to 18 years) were included in this study. QUS was performed on the calcaneus using the Saharatrade mark device (Hologic, USA). SOS and BUA were estimated. Regional reference values of 3299 children were used to determine significant differences between athletes and reference population. The influence of activitiy level, age, height, and weight was estimated using correlation analysis. RESULTS: Sportsmen showed significant (p < 0.05) higher values of the QUS parameters (SOS 1581.1 m/s; BUA 69.7 dB/MHz) compared to the reference data (SOS 1563.9 m/s; BUA 64.2 dB/MHz). Significant correlation was observed between BUA and the level of activity, age, weight, and height (p < 0.01) and between SOS and weight and height (p < 0.05). In the group of soccer players and athlets, significant correlation was found between BUA vs. age and BUA vs. weight (p < 0.05). Furthermore, significant corelation was observed between BUA vs. age and weight in judokas and wrestlers. For the level of activity, a significant correlation to BUA was only found in the group of judokas and wrestlers (p < 0.01). CONCLUSION: An increase in quantitative ultrasound parameters on the calcaneus occurs in children and adolescents with increased physical activity.

Adolescent↗
PubMed2005

[Assessment of skeletal age using a new ultrasound method].

PURPOSE: Determination of skeletal development in children is important. The most used evaluation method is to study left hand X-ray based on the standards depicted by Greulich and Pyle. The aim of our study was to compare the accuracy of a new sonographically based method with the standard method. MATERIAL AND METHODS: 160 consecutive evaluated children and adolescents (77 male, 83 female) who received a X-ray of the left hand were evaluated. Ultrasound examination of the same hand was performed on the same day using the BonAge system (Sunlight Medical Ltd., Israel). This system evaluates the relationship between the velocity of the wave (speed of sound) passing thorough the distal radial and ulna epiphysis and growth, using gender- and ethnicity-based algorithms. Three experienced investigators (U1-U3) analysed the X-ray and assigned bone age scores based on the Greulich and Pyle atlas (G and P). The investigators were blinded to the calendary age (CA) of the patient and also for the BonAge result. Correlation between BonAge system results and G and P was performed using SPSS 12.0.1. RESULTS: In 152 patients BonAge measurement could be performed successfully. The correlation between the three investigators using the G and P method was between 0.977 and 0.980; correlation between the BonAge system and the investigators (U1-U3) was 0.902 and 0.920. The paired t-test showed no significant differences between the BonAge system and the three investigators and also for the comparison between U1 and U2. There were significant differences between U1 vs. U3 and U2 vs. U3 (p < 0.05). DISCUSSION: The BonAge device demonstrates the ability to produce an sufficient assessment of bone age using an ultrasound method. The results are correlated with conventional skeletal age evaluation using the G and P method. Advantages of the ultrasound device are objectivity, lack of ionizing radiation, and easy accessibility. In the case of first investigation X-ray is necessary to look for dissociated skeletal age, dysplasia, and mineralisation.

Adolescent↗
PubMed2005

Design of oligolactone-based scaffolds for bone tissue engineering.

Novel difunctional oligolactone macromers have been synthesized by ring-opening oligomerization of various lactones (L-lactide, glycolide, p-dioxanone) in the presence of suitable diols (propane-1,2-diol, dianhydro-D-glucitol) and subsequent endcapping of the formed oligolactones with methacrylate moieties. Based on these macromers, two fabrication procedures were developed to fabricate highly porous scaffolds and the material properties including in vitro biodegradation behaviour of the resulting polymeric scaffolds were investigated. Preliminary in vitro studies on the cytocompatibility of the fabricated scaffolds and on osteoblast cultivation on the optimized polymeric materials demonstrated that the oligolactide based polymer networks possess an excellent biocompatibility and that they are promising candidates as scaffolds in bone tissue engineering.

3T3 Cells↗
PubMed2004

Comparison of whole-body STIR-MRI and 99mTc-methylene-diphosphonate scintigraphy in children with suspected multifocal bone lesions.

The study was performed to compare whole-body short time inversion recovery (STIR) MR imaging and (99m)Tc-methylene diphosphonate planar scintigraphy in the examination of children with suspected multifocal skeletal malignant lesions. Sixteen patients with known or suspected malignant skeletal disease underwent both whole-body STIR MR imaging and bone scintigraphy. The lesions were described and numbered according to scintigraphic evaluation criteria. Thus, 16 regions were analyzed in each patient for the comparison between the two modalities. Histology was proven in the primary malignant regions. Follow-up MRIs were registered. Scintigraphy and MRI follow-up were evaluated as gold standard. A total of 139 different lesions was observed by both modalities. Baseline whole-body MRI revealed 119 bone lesions in 256 possible sites (46.5%); scintigraphy revealed only 58 lesions (22.6%). Congruence was observed in only four patients (25%). According to the location of the lesion, correlation was observed in 39/139 lesions (28%). In all, 57.5% of the lesions were detected only by MRI and 14.5% of the lesions were detected only by scintigraphy. Whole-body MRI was more sensitive (P<0.001). Of all lesions numbered which could be separated in the initial MRI, whole-body MRI detected 178 lesions in the patients. The results suggest that whole-body MRI using a STIR sequence is an effective radiation free method for examination of children with suspected multifocal bone lesions. MRI showed more lesions than conventional (99m)Tc-methylene diphosphonate scintigraphy. Therefore, whole-body MRI may be feasible as a screening modality for metastatic and skip lesions in osteosarcoma, PNET, Ewing sarcoma and Langerhans cell histiocytosis in children.

Adolescent↗
PubMed2004

Inducible nonviral gene expression in the treatment of osteochondral defects.

OBJECTIVE: The repair of osteochondral defects with chondrocytes genetically modified to express desired growth factors promises great potential in orthopaedic therapy. Controlled expression of the transgenes is required in many instances. The objective of the present study was to demonstrate the inducibility of tetracycline-responsive transgene expression in osteochondral defects in the knee joint filled with genetically modified chondrocyte implants. METHODS: An expression plasmid containing the lacZ gene under the control of the minimal CMV promoter fused to the Tet-responsible element (TRE) as well as the reverse transactivator (rtTA2s-M2) was constructed and used to transfect isolated articular chondrocytes from New Zealand white rabbits. rtTA2s-M2 binds to the TRE in the presence of tetracycline and leads to the transcription of the transgene. Different concentrations of DNA and various DNA:lipid ratios were tested to determine best transfection conditions. Transfection efficiency and inducibility were analysed by histochemical analysis and flow-cytometry. To evaluate the system in vivo, collagen-sponges were seeded with transfected autologous chondrocytes and implanted in osteochondral defects in the knees of NZW-rabbits. Gene expression was induced by doxycycline and 3 weeks later, LacZ-expression in isolated knee joints was evaluated in histological sections by X-gal staining. RESULTS: In vitro 13.5% (+/-1.32) of induced primary chondrocytes were LacZ-positive, while non-induced controls showed a background-staining in 0.6% (+/-0.2). In vivo, upon doxycycline treatment, induction of lacZ-gene-expression could be demonstrated in chondrocytes in 3-week-old, well-integrated implants. CONCLUSION: For the first time, tetracycline-inducible gene expression is demonstrated to work in the treatment of osteochondral defects. This demonstrates the feasibility for a gene therapy-assisted approach using controlled expression of therapeutic growth factors from transplanted genetically modified chondrocytes.

3T3 Cells↗
PubMed2004

Cluster analysis of soft X-ray spectromicroscopy data.

Soft X-ray spectromicroscopy provides spectral data on the chemical speciation of light elements at sub-100 nm spatial resolution. When all chemical species in a specimen are known and separately characterized, existing approaches can be used to measure the concentration of each component at each pixel. In other cases (such as often occur in biology or environmental science), some spectral signatures may not be known in advance so other approaches must be used. We describe here an approach that uses principal component analysis to orthogonalize and noise-filter spectromicroscopy data. We then use cluster analysis (a form of unsupervised pattern matching) to classify pixels according to spectral similarity, to extract representative, cluster-averaged spectra with good signal-to-noise ratio, and to obtain gradations of concentration of these representative spectra at each pixel. The method is illustrated with a simulated data set of organic compounds, and a mixture of lutetium in hematite used to understand colloidal transport properties of radionuclides.

Cluster Analysis↗
PubMed2004

Efficacy of ion-selective probes in early epicardial in vivo detection of myocardial ischemia.

Myocardial hypoxia is accompanied by increased epicardial potassium activity. In this experimental study in rabbits (n = 13), with ion-selective probes, we correlated our findings with an exact evaluation of myocardial oxygen tension, hemodynamic data and arterial and venous blood gas analysis. The epicardial potassium activity had good correlation with these parameters (pm = -0.95, pco = -0.93 and pa = -0.72, pv = -0.96, respectively). Therefore, the clinical use of these electrodes can be recommended for continuous monitoring in intensive care units.

Animals↗
PubMed2003

Effectiveness of the glycoprotein IIb/IIIa antagonist abciximab during percutaneous coronary interventions (PCI) in clinical practice at a single high-volume center.

OBJECTIVE: Randomized controlled trials (RCTs) showed that the glycoprotein (GP) IIb/IIIa antagonist abciximab is able to reduce ischemic complications during percutaneous transluminal coronary interventions (PCIs). Its effectiveness in daily clinical practice in unselected patients remains to be determined. DESIGN, SETTING AND PATIENTS: From 7/1997 until 12/2000, 3310 PCIs were performed at the Heart Center Ludwigshafen. Out of them, 1076 (32.5%) patients were nonrandomly treated with a GP IIb/ IIa antagonist. Patients who were treated with abciximab were matched with patients not treated with abciximab. The matching procedure resulted in 590 pairs of patients. RESULTS: Patients treated with abciximab were more likely to have a history of former PCI (13.7% versus 8.8%, p=0.008) or coronary artery bypass surgery (19.2% versus 12.8%, p=0.003). There were no differences in concomitant diseases, left ventricular function, number of vessels diseased or target vessel. However, patients treated with abciximab had a higher rate of more complex stenosis (> or =B2; 94.4% versus 80.7%, p<0.001) and a longer x-ray exposition (median 486 s versus 422 s, p<0.001). Treatment with abciximab was associated with a significantly lower incidence of the combined endpoint of death, reinfarction or stroke during the hospital stay (2.4% versus 4.4%, p=0.039). This was confirmed after adjustment for confounding parameters (p=0.034). There was no increase in the rate of severe bleeding in the abciximab group (p=0.347). After one year the rates for the combined endpoint were 8.5% in the control group and 6.2% in the abciximab group (univariate analysis, p=0.134; multivariate analysis, p=0.143). CONCLUSION: Treatment with abciximab during PCI in daily clinical practice at a high volume center in patients with a high rate of acute coronary syndromes seems to be as effective as shown in RCTs.

Abciximab↗
PubMed2003

Depleted uranium particles in selected Kosovo samples.

Selected soil samples, collected in Kosovo locations where DU ammunition was expended during the 1999 Balkan conflict, have been investigated by secondary ion mass spectrometry (SIMS), X-ray fluorescence imaging using a micro-beam (micro-XRF) and scanning electron microscopy equipped with an energy dispersive X-ray fluorescence detector (SEM-EDXRF), with the objective to test the suitability of these techniques to identify the presence of small DU particles and measure their size distribution and the 235U/238U isotopic ratio (SIMS). Although the results do not permit any legitimate extrapolation to all the sites hit by the DU rounds used during the conflict, they indicated that there can be "spots ' where hundreds of thousands of particles may be present in a few milligrams of DU contaminated soil. The particle size distribution showed that most of the DU particles were <5 microm in diameter and more than 50% of the particles had a diameter <1.5 microm. Knowledge on DU particles is needed as a basis for the assessment of the potential environmental and health impacts of military use of DU, since it provides information on possible re-suspension and inhalation.

Environmental Exposure↗
PubMed2003

[A head-mounted display system for augmented reality: initial evaluation for interventional MRI].

PURPOSE: To discuss the technical details of a head mounted display with an augmented reality (AR) system and to describe a first pre-clinical evaluation in interventional MRI. METHOD: The AR system consists of a video-see-through head mounted display (HMD), mounted with a mini video camera for tracking and a stereo pair of mini cameras that capture live images of the scene. The live video view of the phantom/patient is augmented with graphical representations of anatomical structures from MRI image data and is displayed on the HMD. The application of the AR system with interventional MRI was tested using a MRI data set of the head and a head phantom. RESULTS: The HMD enables the user to move around and observe the scene dynamically from various viewpoints. Within a short time the natural hand-eye coordination can easily be adapted to the slightly different view. The 3D perception is based on stereo and kinetic depth cues. A circular target with a diameter of 0.5 square centimeter was hit in 19 of 20 attempts. In a first evaluation the MRI image data augmented reality scene of a head phantom allowed good planning and precise simulation of a puncture. CONCLUSION: The HMD in combination with AR provides a direct, intuitive guidance for interventional MR procedures.

Computer Graphics↗
PubMed2003

[Early results of ultrasound based calculation of broadband ultrasound attenuation and speed of sound in children and adolescents suffering from asthma].

PURPOSE: To determine broadband ultrasound attenuation (BUA) and speed of sound (SOS) on the os caicis in asthmatic children. To correlate these findings with sex, age, weight and height, topical steroid intake, and asthma severity grade (ASG). PATIENTS AND METHODS: 178 children (ASG 1 - 3)/(98 m, 80 f; mean age 11.9 +/- 3.1 y) were consecutively chosen from 4/00 to 9/01. Children with any other chronic disease were excluded. BUA and SOS were measured using SAHARA (Hologic lnc. Waltham, USA). Regional normative BUA and SOS data of 3 299 children (obtained with the same system), were used to calculate age-, weight- and height-matched standard-deviation-scores (SDS) for both sexes. Asthma severity grade and steroidal intake were determined. The highest topical steroid dosage was 500 micro g Fluticasone or 800 micro g Budesonide per day. RESULTS: 10/178 children were small and 7/178 tall per age (5.6 %/3.9 %), 11/178 children were light (6.2 %) and 9 heavy per age (5.0 %). 19 and 45 children had reduced BUA and SOS values, respectively. The following rates of reduced values were observed: girls: BUA 15.0 % (12/80), SOS 25.0 % (20/80); boys: BUA 7.1 %, SOS 25.5 % (7/98 and 25/98). Sexual differences were not significant. Reduced SOS-values were associated with higher severity and occurred significantly more frequent at children under steroidal intake (0.09 vs. 0.25 [BUA] and - 0.37 vs. - 0.07 [SOS]). CONCLUSION: Following our results an increase incidence of reduced speed of sound occurs in asthmatic children which is attributed to asthma severity and seems to be negatively influenced even by topically applied low dose steroids. This could be attributed to a steroid induced collagen synthesis deficiency followed by a reduced bone elasticity. Further studies, especially using a longitudinal study design are required to verify these findings.

Adolescent↗
PubMed2002

Fabrication of highly porous scaffold materials based on functionalized oligolactides and preliminary results on their use in bone tissue engineering.

Tissue engineering offers a promising new approach to repair bone defects. Its practical realisation is connected with the development of suitable scaffold materials. In the present work, functionalized oligolactides have been prepared and used as macromers for the scaffold fabrication The developed fabrication process leads to highly porous scaffolds, available in various shapes and sizes, with an open inter-connective pore structure and porosities up to 90%. Degradable or even osteoconductive components as well as biocompatible co-monomers can be used as additives to modulate the scaffold properties. Under in vitro conditions, the scaffolds exhibit a continuous degradation with varying degradation rates depending on their material composition. In vitro studies on the cultivation of osteoblasts on the scaffolds were performed and revealed their excellent biocompatibility. Cell growth on the scaffold surfaces and inside the scaffolds, formation of extracellular matrix and starting mineralization were detected by microscopical and histological analyses. Based on these results the developed materials are well-suited candidates for the design of tailor-made matrices in bone tissue engineering

Journal Article↗
PubMed2002

[Detection of myocardial ischemia by epicardial detection of potassium ion activity].

Early detection of myocardial ischaemia is a central problem in cardiological and cardiosurgical intensive care. A new approach is the use of ion-selective electrodes implanted directly on the myocardium, enabling detection of increased potassium activity as an indication of general hypoxia. After a comprehensive study of the electrode parameters, an animal experiment was carried out, in which it was found that respiration-induced hypoxia resulted in an increase in epicardial potassium activity (p < 0.01). Blood gas analysis performed simultaneously revealed reduced arterial pO2, but no acidosis. Haemodynamic data evidenced hypoxic depression of circulatory parameters. Histological examinations of the myocardium beneath the electrodes revealed typical lymphocytic infiltration. Electron microscopy demonstrated crystolysis in the mitochondria as an early sign of hypoxia, thus confirming the sensitivity of these electrodes. This underscores the potential of ion-selective electrodes for the detection of myocardial ischaemia, and they should now be investigated in the clinical setting.

Animals↗