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R Schmidt

Publications and source records attributed to R Schmidt.

At least 37 records · Page 2Linked to original sources
PubMed2006

Evaluation of GafChromic EBT prototype B for external beam dose verification.

The capability of the new GafChromic EBT prototype B for external beam dose verification is investigated in this paper. First the general characteristics of this film (dose response, postirradiation coloration, influence of calibration field size) were derived using a flat-bed scanner. In the dose range from 0.1 to 8 Gy, the sensitivity of the EBT prototype B film is ten times higher than the response of the GafChromic HS, which so far was the GafChromic film with the highest sensitivity. Compared with the Kodak EDR2 film, the response of the EBT is higher by a factor of 3 in the dose range from 0.1 to 8 Gy. The GafChromic EBT almost does not show a temporal growth of the optical density and there is no influence of the chosen calibration field size on the dose response curve obtained from this data. A MatLab program was written to evaluate the two-dimensional dose distributions from treatment planning systems and GafChromic EBT film measurements. Verification of external beam therapy (SRT, IMRT) using the above-mentioned approach resulted in very small differences between the planned and the applied dose. The GafChromic EBT prototype B together with the flat-bed scanner and MatLab is a successful approach for making the advantages of the GafChromic films applicable for verification of external beam therapy.

Calibration↗
PubMed2006

Long-term effects of the intensification of the transition between inpatient neurological rehabilitation and home care of stroke patients.

OBJECTIVE: To investigate an intensified transition concept between neurological inpatient rehabilitation and home care for long-term effects on the care situation two and a half years after stroke patients' discharge. DESIGN: Controlled clinical trial allocating patients to intervention group (intensified transition on ward II) or control group (standard transition on ward I); patients were allocated to whichever ward had a vacancy. The last follow-up assessment was carried out on average 31 months after discharge. INTERVENTION: The intensified transition concept consisted of therapeutic weekend care, bedside teaching and structured information for relatives during the second phase of the rehabilitation. SUBJECTS: Seventy-one patients and their family carers were included, of which one case dropped out. Therefore 70 family carers--35 individuals in each group-- were available for assessment at long-term follow-up. DATA COLLECTION: Family carers were asked via telephone whether the patient was still alive and if so, where he or she is living--at home or in a nursing home. STATISTICAL METHODS: Binary logistic regression analysis with the care situation (home care versus institutionalized care or deceased) as dependent variable. RESULTS: Two and a half years after discharge (T3) in the intervention group significantly fewer patients were institutionalized (2 versus 5) or deceased (4 versus 11) (P = 0.010). Multivariate analysis showed that besides a higher functional life quality at discharge and lower patient's age, the participation in the intensified transition programme is the third significant predictor for home care at T3. CONCLUSION: Effects of an intensified transition programme can persist over a long-term period. They can sustain home care by reducing institutionalization and mortality.

Aged↗
PubMed2005

Benefits of active motion for joint position sense.

Anterior cruciate ligament (ACL) ruptures lead to a proprioceptive deficit and therefore joint position sense. This study examined whether active motion is better suited than passive motion to address this deficit. Sixty patients with ACL rupture were prospectively randomised into two groups [continuous active motion (CAM)/continuous passive motion (CPM)]. All patients had an ACL reconstruction. An angle reproduction test was used to assess the proprioceptive deficit. The relevant examinations were performed before surgery (pre-op evaluation) and after the seventh postoperative day. No preoperative difference was found between the two groups. After postoperative treatment, the deficit was reduced in both groups. Significantly better results were, however, obtained in the CAM group (CPM, 4.2+/-1.6 degrees; CAM, 1.9+/-1.2 degrees; P<0.001). During the first postoperative week, a CAM device produced a significantly greater reduction in the proprioceptive deficit and should be the first choice in immediately postoperative rehabilitation after ACL replacement.

Adolescent↗
PubMed2005

Regional variability in the prevalence of cerebral white matter lesions: an MRI study in 9 European countries (CASCADE).

White matter lesions (WML) on MRI of the brain are common in both demented and nondemented older persons. They may be due to ischemic events and are associated with cognitive and physical impairments. It is not known whether the prevalence of these WML in the general population differs across European countries in a pattern similar to that seen for coronary heart disease. Here we report the prevalence of WML in 1,805 men and women drawn from population-based samples of 65- to 75-year-olds in ten European cohorts. Data were collected using standardized methods as a part of the multicenter study CASCADE (Cardiovascular Determinants of Dementia). Centers were grouped by region: south (Italy, Spain, France), north (Netherlands, UK, Sweden), and central (Austria, Germany, Poland). In this 10-year age stratum, 92% of the sample had some lesions, and the prevalence increased with age. The prevalence of WML was highest in the southern region, even after adjusting for differences in demographic and selected cardiovascular risk factors. Brain aging leading to disabilities will increase in the future. As a means of hypothesis generation and for health planning, further research on the geographic distribution of WML may lead to the identification of new risk factors for these lesions.

Aged↗
PubMed2005

Risk factors for progression of brain atrophy in aging: six-year follow-up of normal subjects.

OBJECTIVES: To determine the rate of brain atrophy in neurologically asymptomatic elderly and to investigate the impact of baseline variables including conventional cerebrovascular risk factors, APOE epsilon4, and white matter hyperintensity (WMH) on its progression. METHODS: We assessed the brain parenchymal fraction at baseline and subsequent annual brain volume changes over 6 years for 201 participants (F/M = 96/105; 59.8 +/- 5.9 years) in the Austrian Stroke Prevention Study from 1.5-T MRI scans using SIENA (structural image evaluation using normalization of atrophy)/SIENAX (an adaptation of SIENA for cross-sectional measurement)(www.fmrib.ox.ac.uk/fsl). Hypertension, cardiac disease, diabetes mellitus, smoking, and regular alcohol intake were present in 64 (31.8%), 60 (29.9%), 5 (2.5%), 70 (39.3%), and 40 (20.7%) subjects, respectively. Plasma levels of fasting glucose (93.7 +/- 18.6 mg/dL), glycated hemoglobin A (HbA1c; 5.6 +/- 0.7%), total cholesterol (228.3 +/- 40.3 mg/dL), and triglycerides (127.0 +/- 75.2 mg/dL) were determined. WMH was rated as absent (n = 56), punctate (n = 120), early confluent (n = 14), and confluent (n = 11). RESULTS: The baseline brain parenchymal fraction of the entire cohort was 0.80 +/- 0.02 with a mean annual brain volume change of -0.40 +/- 0.29%. Univariate analysis demonstrated a higher rate of brain atrophy in older subjects (p = 0.0001), in those with higher HbA1c (p = 0.0001), higher body mass index (p = 0.02), high alcohol intake (p = 0.04), severe WMH (p = 0.03), and in APOE epsilon4 carriers (p = 0.07). Multivariate analysis suggested that baseline brain parenchymal fraction, HbA1c, and WMH score explain a major proportion of variance in the rates of brain atrophy in the cohort (corrected R2 = 0.27; p = 0.0001). CONCLUSIONS: Neurologically asymptomatic elderly experience continuing brain volume loss, which appears to accelerate with age. Glycated hemoglobin A (HbA1c) was identified as a risk factor for a greater rate of brain atrophy. Clustering of factors associated with the so-called metabolic syndrome in subjects with high HbA1c suggests a link between this syndrome and late-life brain tissue loss.

Age Distribution↗
PubMed2005

Discrimination of white matter lesions and multiple sclerosis plaques by short echo quantitative 1H-magnetic resonance spectroscopy.

Multiple sclerosis (MS) plaques and age related white matter lesions (WML) are of similar morphological appearance on T2 weighted MRI. Therefore their differentiation is sometimes crucial. Proton magnetic resonance spectroscopy ((1)H-MRS) adds metabolic information to conventional imaging and may help to distinguish inflammatory MS plaques from vascular related WML. This study was performed to evaluate the metabolite pattern in MS plaques and WML. 15 MS patients, 14 elderly individuals with WML and 16 controls were investigated by conventional MRI and short echo quantitative (1)H-MRS (TE: 30ms, TR: 3000ms). The mean metabolite concentrations in normal control white matter (NCWM), MS plaques and WML were: t-NAA: 8.96 mmol/l (SD: 0.93) vs 6.79 mmol/l (SD: 1.99) vs 7.18 mmol/l (SD: 1.41); Cho:1.66 mmol/l (SD: 0.4) vs 1.49 mmol/l (SD: 0.45) vs 1.46 mmol/l (SD: 0.34); PCr:5.64 mmol/l (SD: 0.83) vs 4.9mmol/l (SD: 1.3) vs 4.95 mmol/l (SD: 0.86); myo-Ins: 4.57 mmol/l (SD:1.05) vs 6.34 mmol/l (SD: 2.03) vs 4.5 mmol/l (SD: 0.96). t-NAA reduction in MS plaques and WML was significant compared with controls (p <or= 0.001). MS plaques showed significantly elevated myo- Ins concentrations compared with controls (p = 0.002) and to WML (p = 0.003). In summary MS plaques and WML show a decrease in their t-NAA concentrations compared with controls. Elevated concentrations of myo-Ins in MS plaques but not in WML makes this metabolite of special interest for their differentiation.

Adult↗
PubMed2005

The CERN Large Hadron Collider as a tool to study high-energy density matter.

The Large Hadron Collider (LHC) at CERN will generate two extremely powerful 7 TeV proton beams. Each beam will consist of 2808 bunches with an intensity per bunch of 1.15x10(11) protons so that the total number of protons in one beam will be about 3x10(14) and the total energy will be 362 MJ. Each bunch will have a duration of 0.5 ns and two successive bunches will be separated by 25 ns, while the power distribution in the radial direction will be Gaussian with a standard deviation, sigma=0.2 mm. The total duration of the beam will be about 89 mus. Using a 2D hydrodynamic code, we have carried out numerical simulations of the thermodynamic and hydrodynamic response of a solid copper target that is irradiated with one of the LHC beams. These calculations show that only the first few hundred proton bunches will deposit a high specific energy of 400 kJ/g that will induce exotic states of high energy density in matter.

Journal Article↗
PubMed2005

Cement leakage during vertebroplasty: an underestimated problem?

Overall, vertebroplasty has a low complication rate. Nevertheless, severe complications can occur. The majority of these are related to cement extrusion. The rate of cement leakage is often obtained by X-ray, with only a single leak registration per vertebra. Detection rate of leaks in comparison with CT and inter-observer reliability for X-ray is, in large parts, unknown. We conducted this study to determine the value of fluoroscopy and X-ray used to detect cement leakage as compared to CT scans. Intraoperative findings in lateral fluoroscopy by the surgeon, and postoperative findings in X-rays by two orthopaedic surgeons, were compared with CT scans for the same study group. Multiple cement leakage was considered, and agreement rate was determined. The detection rate for leaks was 34% for lateral X-ray and 48% for lateral and AP view. Additional AP views only enhanced the detection of leaks in the segmental veins. The agreement rate between fluoroscopy/X-ray and CT scans ranged between 66% and 74%, while inter-observer reliability showed only fair agreement. The rate of cement leaks in vertebroplasty is high if multiple leaks are considered in CT scans. Detection rates using X-rays are low and complicated by only fair inter-observer agreement. Leaks in the basivertebral veins are frequently misinterpreted and can lead to severe complications. Therefore, CT scans should be obtained to calculate the exact leakage rate and to assess persistent or new pain occurring postoperatively.

Aged↗
PubMed2005

[The EU Bathing Water Directive. Risk assessment and standards].

In an attempt to reduce the risk of infection in natural bathing waters the European Union is in the process of improving the Bathing Water Directive 76/160/EWG, which regulates the safety of such waters. The proposal contains several positive innovations which will improve the protection of the bathers: (1) health-related indicators, (2) harmonized detection methods, (3) requirements for active bathing water management, and (4) stricter standards for coastal waters. One of the most salient features of the current draft is the introduction of bacterial standards that are more stringent for coastal than for fresh waters. This decision on different standards seems unjustified: it was taken solely on the grounds that in two epidemiological studies-one carried out in coastal, the other in fresh waters-the maximum excess rate of gastroenteritis among bathers in coastal waters was higher than among bathers in fresh waters. However, it was not taken into account that the concentrations of bacterial indicators at which the gastroenteritis rate began to increase was nearly identical in both studies. The ratio between the standard concentrations of E. coli and intestinal enterococci in the draft was set at 2.5. This value does not correspond to the ratio found in German surface waters with low pollution levels, with ratios ranging from 2.7 to 4.0, and to the even higher ratios found in raw and treated sewage effluents. As a consequence in a majority of cases the non-compliance of bathing waters in Germany would be caused exclusively by a violation of E. coli standards. In assessing risks of infection it must also be taken into account that the adequacy of E. coli and intestinal enterococci for signaling the presence of viruses in water is far from optimal. The decay of viruses in water-estimated by the decay of bacteriophages-was found to be substantially slower than the die-off of indicator bacteria.

Bathing Beaches↗
PubMed2005

[Removal of a thoracic impaling agent without direct observation. The significance of pre-operative diagnosis].

Impalement injuries are uncommon and only occasional reports exist in the literature, resulting in non standardized approaches. Depending on the location, completely different combinations of injuries occur, making every impalement unique. Nevertheless some basic principles for dealing with impalements exist. These principles, and some controversial statements in the literature on the value of preoperative diagnostics, especially CT, are discussed using the example of a spectacular thoracic impalement by a 2 x 2 cm square metal pole. Our deviation from the principal of removing an impaling object only under direct observation in this special case is also discussed.

Adult↗
PubMed2005

[Diabetic muscle infarction-an orthopedic disease pattern?].

Diabetic muscle infarction (DMI) is a largely unfamiliar disease. It affects mainly patients around 40 years of age with long-standing diabetes and concomitant end-organ complications. The symptoms represent a classic pattern of a musculoskeletal disease with muscle pain without trauma, swelling, and functional impairment. Although its short-term prognosis is good, with improvement of the symptoms over weeks or months under analgesia and rest, a high recurrence rate of up to 60% can be observed. Additionaly, the long-term survival of patients after DMI is reduced mostly due to major vascular complications. Since many diabetic patients are in orthopedic care for musculoskeletal disorders, the orthopedic surgeon should be aware of this disease to avoid unnecessary invasive diagnostic procedures and initiate suitable therapy. Furthermore, a better knowledge of the disease could lead to definite conclusions regarding its real incidence and aid in establishing new therapeutic measures for prophylaxis and better long-term survival.

Diabetic Angiopathies↗
PubMed2005

Reactivity of Langerhans cells in human reconstructed epidermis to known allergens and UV radiation.

Epidermal Langerhans cells are the outmost guards of our immune defence system. These cells are directly involved in phenomena such as contact hypersensitivity and UV-induced immunosuppression. Some years ago we succeeded in introducing CD34(+)-derived Langerhans cells into a reconstructed human epidermis. Here we describe their reactivity after topical exposure of the reconstructed epidermis to known allergens, allergen-inducible cytokines, irritants and UV irradiation. Exposure to allergens for 24 h resulted in an activated appearance of the Langerhans cells and in some cases a decrease in their number. Concomitantly, IL-1beta and CD86 mRNA over-expressions were detected in the reconstructed epidermis. A topical treatment with TNF-alpha or IL-1beta revealed that both cytokines induced an activated appearance of the Langerhans cells as early as 4 h following application. Irritants had no effect on the integrated Langerhans cells. Exposure of the reconstructed epidermis to Solar Simulated Radiation caused a dramatic decrease in the number of Langerhans cells and a loss of dendricity in the remaining cells 24 h after irradiation. The topical application of a large spectrum UVA/B filter before irradiation prevented these UV-induced alterations. In our hands, this model provides a promising tool to evaluate the sensitization potential of new compounds and to validate the efficacy of sunscreens to prevent UV-induced immunosuppression.

Allergens↗
PubMed2005

[Changes of the late acoustically evoked potentials in postlingually deaf patients with cochlear implants].

BACKGROUND: The speech recognition performances in postlingually deaf patients, which had a long duration of deafness, seem to be poorer than in patients with a short duration of deafness. The reason could be a functional reorganization in the auditory cortex. A long time of auditory deprivation may decrease neuronal activity in the auditory related cortices. As the late acoustically evoked potentials are generated in this region, we compared the speech recognition performances and also the late acoustically evoked potentials with the individual duration of deafness in a series of postlingually deaf patients. METHODS: In 9 patients (cochlear implant (CI), MED EL) with postlingual deafness the late acoustically evoked potentials and the HSM-set-test on the quiet were measured. Additionally 1 patient with prelingual deafness was examined. The CI-operation was done, when he was 14 years old. The relations between the late acoustically evoked potentials and the speech recognition performances in dependence of the duration of deafness were examined. RESULTS: Typical late acoustically evoked potentials could be measured in 3 patients only. The speech recognition in these patients was very good. The longest time of deafness in these patients was 6 years. In 6 patients the minimum duration of deafness was 12 years. Here were measured the N1-potentials only, the P2- and the N2-potentials were absent. In these patients the scores of the HSM-set-test were lower than in the others. In the 15-years old patient with prelingual deafness the speech recognition was absent. The late acoustically evoked potentials of this patient showed an atypical form. CONCLUSIONS: The results of this study showed a correlation between the duration of deafness, the forms of the late acoustically evoked potentials and the speech perception. The duration of deafness preceding CI-implantation should be very small in deaf children and in postlingually deaf patients.

Adolescent↗
PubMed2005

[Extracorporeal blood purification in severe liver failure with the albumin dialysis MARS -- impact on relevant intensive care parameters].

Extracorporeal liver support methods have been tested for over 50 years now. Standard techniques of blood purification like dialysis, adsorption, hemo- and plasma filtration as well as bioreactor-based approaches using liver cells or tissues have been used. Most clinical experience, however, is limited to use in acute liver failure (ALF). Since 1993, the Molecular Adsorbent Recirculating System (MARS) has been used clinically -- a system that combines dialysis, filtration and adsorption in a biocompatible method. Human serum albumin (HSA) acts as a selective molecular adsorbent binding protein-bound compounds like bile acids or bilirubin. These substances can contribute to the maintenance or even further aggravation of liver failure. They are linked with the pathogenesis of hyperdynamic hypotonic circulation, hepatic encephalopathy, hepatorenal syndrome, impaired hepatic protein synthesis, and intractable pruritus seen in chronic liver failure. HSA takes over the toxic substances from a patient's blood and passes through a remote detoxification process including bicarbonate-dialysis and a two-step adsorption. It is then recirculated in the patient's blood. Up to today, more than 4000 patients have been treated in approximately 16,000 single sessions. Thus, MARS represents the most frequently used liver support method at the present time. In addition to ALF, mainly acute decompensations of chronic liver failures (ACLF) have been treated. The impact of the extracorporeal treatment on relevant medical parameters of intensive care medicine is discussed with regard to the specific situation of the liver-failure patient (susceptibility to infection, atypical picture and course of infection, coagulation disorders and bleeding tendencies).

Acute Kidney Injury↗
PubMed2005

[Vertebroplasty--basic science, indications and technique].

INTRODUCTION: Vertebroplasty is a relatively new procedure for the treatment of vertebral body fractures of different origin. Due to early promising results the rate of performed procedures increases constantly. Indeed an increasing number of partially severe complications are reported. A summary of the existing findings seems therefore necessary. METHODS: On the basis of a medline inquiry important aspects of vertebroplasty in the fields of basic science, diagnostics, indications, contraindications, technique, results and complications were compiled. RESULTS: Especially for the field of indications, possible longterm effects and for the "ideal" technique open questions exist, mainly due to missing prospective, randomized long-term clinical trials. CONCLUSIONS: A final assessment of the significance of vertebroplasty for osteoporotic fractures in comparison to conservative treatment is actually not possible. In contrast vertebroplasty is a therapeutical option for malignomas in selected cases.

Biomechanical Phenomena↗
PubMed2005

Identification and characterization of a novel retroviral-like aspartic protease specifically expressed in human epidermis.

Proteases play a pivotal role in epidermal differentiation and desquamation. Separation of a total protein extract from human reconstructed epidermis by two-dimensional gel electrophoresis and subsequent peptide analysis of a specific protein spot identified a new protein exhibiting similarities with the retroviral aspartic protease family. Cloning of the corresponding full-length cDNA revealed an open reading frame encoding for a new protease of 343 amino acids, containing a putative aspartic protease catalytic domain. We named this protein Skin ASpartic Protease (SASPase). RT-PCR and northern blot analysis of various human tissues revealed that SASPase was specifically expressed within the epidermis. Immunohistochemical analysis showed a particularly intense expression restricted to the granular layers, whereas in diseased skin, its expression was changed. Western blot analysis, using a monoclonal antibody, revealed the expression of two forms of the enzyme: a 28 kDa putative proform and the active 14 kDa form. Recombinant truncated SASPase (SASP28) was generated from a prokaryotic expression system in Escherichia coli as a fusion protein with GST. SASP28 degraded insulin and to a lesser extent casein with a pH optimum of 5. As seen for retroviral proteases, an auto-activation processing was evidenced, generating a 14 kDa protein (SASP14). Site-directed mutagenesis inhibited auto-activation of the enzyme. Indinavir, a potent HIV protease inhibitor used in AIDS therapy, had a significant inhibitory effect on rSASPase auto-activation, which could explain its side effects on skin.

Amino Acid Sequence↗
PubMed2005

Odor and chemesthesis from brief exposures to TXIB.

UNLABELLED: An experiment explored ability of subjects to detect vapors of the plasticizer TXIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) and ethanol via olfaction and via ocular and nasal chemesthesis, i.e. chemically stimulated feel. Testing, tailored to the sensitivity of each subject, produced psychometric functions for individuals. Olfactory detection of TXIB began at concentrations below 1 ppb (v/v), with 50% correct detection at 1.2 ppb. (Comparable detection for ethanol occurred almost two orders of magnitude higher.) Chemesthetic detection of TXIB began at about 500 ppb, with 50% correct detection at 2.1 ppm for the eye and 4.6 ppm for the nose, both close to saturated vapor concentration. (Comparable detection for ethanol occurred essentially three orders of magnitude higher.) Suggestions that TXIB plays a role in generation of irritative symptoms at concentrations in the range of parts-per-billion need to reckon with a conservatively estimated 200-fold gap between the levels putatively 'responsible' for the symptoms and those even minimally detectable via chemesthesis. Neither the variable of exposure duration nor that of mixing offers a likely explanation. Inclusion of ethanol in the study allowed comparisons pertinent to issues of variability in human chemoreception. An interpretation of the psychometric functions for individuals across materials and perceptual continua led to the conclusion that use of concentration as the metric of detection in olfaction inflates individual differences. PRACTICAL IMPLICATIONS: This study indicated that the plasticizer TXIB could contribute odor at concentrations in the range of parts-per-billion, but could hardly contribute sensory irritation per se, as alleged in reports of some field studies where TXIB has existed amongst many other organic compounds.

Adolescent↗