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Biomedical subjects

R Lange

Publications and source records attributed to R Lange.

At least 37 records · Page 2Linked to original sources
PubMed2005

Hemodynamic performance and incidence of patient-prosthesis mismatch of the complete supraannular perimount magna bioprosthesis in the aortic position.

BACKGROUND: Complete supraannular placement and smaller stent design allow the implantation of a Perimount Magna bioprosthesis with a larger inner diameter than that of a standard Perimount. This study compares the hemodynamic performance and the incidence of patient-prosthesis mismatch (PPM) of both prostheses. METHODS: 128 patients underwent aortic valve replacement, receiving either a Magna (n = 57) or a standard (n = 71) prosthesis. Inner aortic annulus diameter was measured intraoperatively by a hegar dilator to match echocardiographically obtained results to the annulus diameter instead of matching them to labelled valve size. RESULTS: The Magna was significantly superior with respect to mean pressure gradient and effective orifice area in patients with an annulus diameter of 22-23 mm. In patients with an annulus diameter < 22 mm or > 23 mm, there was a non-significant trend towards superior hemodynamics in the Magna group. Severe PPM (effective orifice area index < or = 0.65 cm (2)/m (2)) was present in 11.1% (Magna) vs. 42.1% (Standard) of patients with an annulus diameter < 22 mm; in 0% (Magna) vs. 13.8% (Standard) with an annulus diameter of 22-23 mm; no PPM was seen in patients with annulus diameter > 23 mm in both groups. CONCLUSIONS: The Perimount Magna had a significantly reduced incidence of patient-prosthesis mismatch and superior hemodynamics compared to the standard Perimount.

Age Factors↗
PubMed2005

Cardiac magnetic resonance imaging: long term reproducibility of the late enhancement signal in patients with chronic coronary artery disease.

OBJECTIVE: To determine long term reproducibility of the late enhancement (LE) signal in contrast enhanced magnetic resonance imaging (MRI) and potential changes of the signal after revascularisation. METHODS: 33 patients (29 men, mean (SD) 61 (11) years) with coronary artery disease (CAD) and left ventricular dysfunction (ejection fraction 30 (7)%) underwent two contrast enhanced MRI procedures within 9 (3) months. Fifteen patients (group A: 14 men, 59 (12) years) had no interventions between the two studies. Eighteen patients underwent revascularisation after MRI 1 (group B: 15 men, 62 (9) years). Changes in the LE signal between the first and second MRIs were investigated in both groups as well as intraobserver and interobserver variabilities for delineation of the signal. RESULTS: The LE signal was highly reproducible in groups A and B for segmental analysis (concordance 86% v 82%, respectively; kappa = 0.70 v 0.67) and summed scores (group A: r = 0.97, p < 0.001; group B: r = 0.93, p < 0.001). The LE signal was quantified as 27 (27) cm3 in group A versus 30 (16) cm3 in group B in the first MRI and 26 (25) cm3 versus 30 (15) cm3, respectively, for the second MRI (both not significant). Moreover, low intraobserver and interobserver variabilities were observed in segmental analysis (kappa = 0.86 and 0.74, respectively, for group A, and kappa = 0.87 and 0.82, respectively, for group B). CONCLUSION: In patients with chronic CAD, the LE signal in contrast enhanced MRI is very stable over an extended time period. These results further characterise contrast enhanced MRI as a useful tool for myocardial viability assessment. Low intraobserver and interobserver variabilities promise robustness of the method for clinical application.

Aged↗
PubMed2004

Efficacy of 1,000 mg effervescent acetylsalicylic acid and sumatriptan in treating associated migraine symptoms.

Recently a new effervescent acetylsalicylic acid (ASA) tablet with high buffering capacity has been developed. In this double-blind, 3-arm, multicenter, parallel-group study, 433 patients were treated either with 1,000 mg effervescent ASA or 50 mg encapsulated sumatriptan or placebo. The primary endpoint was the percentage of patients with complete remission of the 3 accompanying symptoms nausea, photophobia and phonophobia within 2 h after intake of the study drug. 43.8% of patients treated with ASA, 43.7% of patients treated with sumatriptan and 30.9% of patients treated with placebo showed complete remission of all 3 accompanying symptoms (p < 0.05 for ASA and sumatriptan vs. placebo). Both active treatments were superior to placebo regarding the individual symptoms photophobia and phonophobia, but not for nausea. The percentage of patients with reduction in headache severity from moderate or severe to mild or no pain (secondary objective) was 49.3% for ASA, 48.8% for sumatriptan and 32.9% for placebo. All active treatments were superior to placebo (p < 0.05). 25.3, 24.4 and 14.5% of patients treated with ASA, sumatriptan or placebo were pain free at 2 h. Drug-related adverse events were reported in 3.9, 4.7 and 6.7% of patients treated with placebo, ASA or sumatriptan. The study showed that administration of effervescent ASA leads to remission of the migraine symptoms nausea, photophobia and phonophobia, reduces migraine headache and is comparable to sumatriptan.

Adolescent↗
PubMed2004

Measurement of the total active 8B solar neutrino flux at the Sudbury Neutrino Observatory with enhanced neutral current sensitivity.

The Sudbury Neutrino Observatory has precisely determined the total active (nu(x)) 8B solar neutrino flux without assumptions about the energy dependence of the nu(e) survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27(stat)+/-0.38(syst) x 10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Deltam(2)=7.1(+1.2)(-0.6) x 10(-5) eV(2) and theta=32.5(+2.4)(-2.3) degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.

Journal Article↗
PubMed2004

Constraints on nucleon decay via invisible modes from the Sudbury Neutrino Observatory.

Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to "invisible" modes, such as n-->3nu. The analysis was based on a search for gamma rays from the deexcitation of the residual nucleus that would result from the disappearance of either a proton or neutron from 16O. A limit of tau(inv)>2 x 10(29) yr is obtained at 90% confidence for either neutron- or proton-decay modes. This is about an order of magnitude more stringent than previous constraints on invisible proton-decay modes and 400 times more stringent than similar neutron modes.

Journal Article↗
PubMed2004

Aortopulmonary window with ventricular septal defect and pulmonary atresia: prenatal diagnosis and successful early surgical correction.

We report a case in which aortopulmonary window (APW) in combination with pulmonary atresia was diagnosed correctly in a neonate by echocardiography. Prenatal echocardiography showed progression of tetralogy of Fallot to pulmonary atresia with retrograde pulmonary perfusion, concealing the concomitant APW in fetal life. Due to intractable heart failure, primary correction was successfully performed at the age of 4 weeks (weight 2280 g).

Adult↗
PubMed2004

Introital ultrasound of the lower genital tract before and after colposuspension: a 4-year objective follow-up.

OBJECTIVE: To assess the topography of the bladder neck by introital ultrasound before and after open colposuspension. METHODS: Three hundred and ten women with urodynamically proven stress urinary incontinence were included in this long-term study to investigate the position and function of the bladder neck at rest and during straining. Height (H), distance (D), and urethrovesical angle of the bladder neck (beta) were measured by means of preoperative and postoperative introital ultrasound. Women were followed up; 152 of them (49%) completed 48 months of follow-up. RESULTS: At the 6-month follow-up examination, 90.0% of the women were continent (279/310), 3.5% (11/310) showed voiding difficulties, 3.5% (11/310) had urgency, and 1.6% (5/310) had developed de novo urge incontinence. At the 48-month follow-up, 76.8% of the patients were still continent. All postoperative measurements yielded significantly lower values for angle beta at rest and during straining compared with the preoperative results (P < 0.0001). The median linear movement of the bladder neck during straining decreased from 18.0 mm before surgery to 6.4 mm at the 48-month follow-up (P < 0.0001). The median level of ventrocranial elevation of the vesicourethral junction was 14.3 mm immediately after surgery, 9.9 mm after 6 months and 6.6 mm after 48 months. The degree of surgical bladder-neck elevation was associated with postoperative urgency/de novo urge incontinence (P < 0.0001) and voiding difficulty (P < 0.0001). CONCLUSIONS: The colposuspension procedure reduces angle beta at rest and during straining, restricts linear movement with straining, and elevates the bladder neck. Perioperative introital ultrasound improves understanding of this surgical procedure and might help to prevent postoperative complications.

Adult↗
PubMed2004

[35-year old male with fever and round mass of the liver].

A 35 year old male suffered from fever till 39 degrees C and malaise since 6 months; infectious or neoplastic causes have been ruled out. Ultrasonography revealed a hypoechoic lesion of 75 mm diameter in the liver. The histologic examination of the needle biopsy showed an inflammatory process, and the final diagnosis was inflammatory pseudotumor. EBV specific LMP-1 protein was detected within the tumor immunohistochemically. A liver segment resection was performed, and the patient has been well and without fever since then for 18 months. Inflammatory pseudotumor is a rare but important differential diagnosis in cases of hypoechoic liver lesions associated by fever, if there is no abscess or malignancy. The diagnosis must be confirmed histologically, because imaging techniques cannot reliably classify the lesion.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Prevalence and risk factors of hepatitis C infection after cardiac surgery in childhood before and after blood donor screening.

BACKGROUND: Since 1974, the risk of acquiring non-A non-B hepatitis by blood transfusion is well known. In 1999, children having had polytransfusions (group 1) after cardiac surgery prior to the establishment of routine blood donor screening could be identified as a risk group for hepatitis C (HCV) infection. PATIENTS AND METHODS: In 1991, Germany began screening blood donors for hepatitis C. To describe the risk after the implementation of blood donor screening, we studied 211 children (group 2) having had open heart surgery after 1991 and compared prevalence for anti-HCV antibodies and known risk factors to group 1. RESULTS: None of the 211 patients with cardiac surgery after 1991 had detectable anti-HCV antibodies, compared to 67 of the 458 patients (14.6%) of group 1 (p < 0.001). The mean number of operations in both groups was virtually the same (mean 1.7 +/- 0.9 in group 1, mean 1.6 +/- 0.9 in group 2, p = 0.075), whereas the total number of blood products per patient differed significantly (group 1 mean 8 +/- 17.6, group 2 mean 3.5 +/- 2.8; p < 0.001). Multivariate analysis of risk factors demonstrates affiliation to group 1, transfusion of fresh blood, warm whole blood, heparinized blood (p < 0.001) and plasma (p = 0.004) as significant. CONCLUSION: After the implementation of blood donor screening, the risk for HCV infection after cardiac surgery in childhood dropped significantly from 14.6% to < 0.5%. These data show the necessity of HCV screening for patients at risk (operations before 1991) and do not favor a general screening for all patients.

Adolescent↗
PubMed2004

Impairment of cardiovascular autonomic control in patients early after cardiac surgery.

OBJECTIVE: Impairment of the baroreceptor reflex activity reflects an alteration of the autonomous regulation of the cardiovascular system and has proven to predict fatal outcome in patients after acute myocardial infarction. The following study was performed to analyse the baroreceptor sensitivity, heart rate variability and blood pressure variability in patients early after coronary surgery. METHODS: Twenty-five male patients undergoing coronary artery bypass were examined in a prospective study; normal values were obtained from healthy volunteers. Arterial pressure signals were recorded from a radial artery catheter for 30 min preoperatively and in short intervals after surgery. Mechanical manipulations and pharmacological interventions were avoided during the sampling periods. Baroreflex function was calculated according to the dual sequence method, heart rate variability and blood pressure variability were calculated including nonlinear methods. RESULTS: Initial values of the patients did not differ from healthy volunteers. The strength of baroreflex sensitivity (increase in blood pressure causing a synchronous decrease of heart rate) is low 2 h postoperatively. The number of delayed tachycardic changes of heart rate, which are caused by sympathetic activation, is only moderately reduced as compared to values obtained from healthy volunteers. Heart rate variability is widely unchanged as compared to preoperative values; blood pressure variability showed an increase of low-frequency components, again indicating sympathetic predominance. Nonlinear analyses revealed reduced system complexity at the beginning of the postoperative course. CONCLUSION: Obviously, there is a vagal suppression 20 h after surgery, while the sympathetic tonus works in a normal range. This unbalanced interaction of the autonomous systems is similar to findings in patients after myocardial infarction. The predictive value of these markers has to be elucidated in further clinical studies.

Aged↗
PubMed2004

Placebo-controlled comparison of effervescent acetylsalicylic acid, sumatriptan and ibuprofen in the treatment of migraine attacks.

Acetylsalicylic acid (ASA) in combination with metoclopramide has been frequently used in clinical trials in the acute treatment of migraine attacks. Recently the efficacy of a new high buffered formulation of 1000 mg effervescent ASA without metoclopramide compared to placebo has been shown. To further confirm the efficacy of this new formulation in comparison with a triptan and a nonsteroidal anti-inflammatory drug (ibuprofen) a three-fold crossover, double-blind, randomized trial with 312 patients was conducted in Germany, Italy and Spain. Effervescent ASA (1000 mg) was compared to encapsulated sumatriptan (50 mg), ibuprofen (400 mg) and placebo. The percentage of patients with reduction in headache severity from moderate or severe to mild or no pain (primary endpoint) was 52.5% for ASA, 60.2% for ibuprofen, 55.8% for sumatriptan and 30.6% for placebo. All active treatments were superior to placebo (P < 0.0001), whereas active treatments were not statistically different. The number of patients who were pain-free at 2 h was 27.1%, 33.2%, 37.1% and 12.6% for those treated with ASA, ibuprofen, sumatriptan or placebo, respectively. The difference between ASA and sumatriptan was statistically significant (P = 0.025). With respect to other secondary efficacy criteria and accompanying symptoms no statistically significant differences between ASA and ibuprofen or sumatriptan were found. Drug-related adverse events were reported in 4.1%, 5.7%, 6.6% and 4.5% of patients treated with ASA, ibuprofen sumatriptan or placebo. This study showed that 1000 mg effervescent ASA is as effective as 50 mg sumatriptan and 400 mg ibuprofen in the treatment of migraine attacks regarding headache relief from moderate/severe to mild/no pain at 2 h. Regarding pain-free at 2 h sumatriptan was most effective.

Adult↗
PubMed2004

High pressure, an alternative approach to understand protein misfolding diseases.

Protein folding is essential for the flow of genetic information to biological activity. A failure in this process can result in disease, by causing cell damage and sometimes death. The misfolding of proteins often induces their aggregation, initiating the fibril formation seen in a range of human and animal diseases. Because misfolding and aggregation are of fundamental importance in vivo, there is currently great interest in understanding their mechanisms. To gain insight into the folding and unfolding processes of proteins, for nearly a century, an original biophysical approach has been successfully used: the application of high hydrostatic pressure combined with various spectroscopic and kinetic techniques. Because high pressure provides new insight into protein structure and folding which cannot be obtained by other techniques, the conformations of pressure-induced unfolding intermediates and species involved in the initial states of aggregation of proteins associated with specific diseases are currently being investigated. Our contention is that by exploring folding kinetics, misfolding pathways and stability under pressure, it will be possible to understand the mechanisms of amyloidogenesis, with the ultimate goal to design therapeutic strategies to prevent progression of the disease.

Amyloid↗
PubMed2003

Characterization of the pressure-induced intermediate and unfolded state of red-shifted green fluorescent protein--a static and kinetic FTIR, UV/VIS and fluorescence spectroscopy study.

The green fluorescence proteins (GFP) are widely used as reporters in molecular and cell biology. For their use it in high-pressure microbiology and biotechnology studies, their structural properties, thermodynamic parameters and stability diagrams have to be known. We investigated the pressure stability of the red-shifted green fluorescent protein (rsGFP) using Fourier-transform infrared spectroscopy, fluorescence and UV/Vis spectroscopy. We found that rsGFP does not unfold up to approximately 9kbar at room temperature. Its unique three-dimensional structure is held responsible for the high-pressure stability. At higher temperatures, its secondary structure collapses below 9kbar (e.g. the denaturation pressure at 58 degrees C is 7.8kbar). The analysis of the IR data shows that the pressure-denatured state contains more disordered structures at the expense of a decrease of intramolecular beta-sheets. As indicated by the large volume change of DeltaV degrees (u) approximately -250(+/-50)mlmol(-1) at 58 degrees C, this highly cooperative transition can be interpreted as a collapse of the beta-can structure of rsGFP. For comparison, the temperature-induced unfolding of rsGFP has also been studied. At high temperature (T(m)=78 degrees C), the unfolding resulted in the formation of an aggregated state. Contrary to the pressure-induced unfolding, the temperature-induced unfolding and aggregation of GFP is irreversible. From the FT-IR data, a tentative p,T-stability diagram for the secondary structure collapse of GFP has been obtained. Furthermore, changes in fluorescence and absorptivity were found which are not correlated to the secondary structural changes. The fluorescence and UV/Vis data indicate smaller conformational changes in the chromophore region at much lower pressures ( approximately 4kbar) which are probably accompanied by the penetration of water into the beta-can structure. In order to investigate also the kinetics of this initial step, pressure-jump relaxation experiments were carried out. The partial activation volumes observed indicate that the conformational changes in the chromophore region when passing the transition state are indeed rather small, thus leading to a comparably small volume change of -20 ml mol(-1) only. The use of the chromophore absorption and fluorescence band of rsGFP in using GFP as reporter for gene expression and other microbiological studies under high pressure conditions is thus limited to pressures of about 4kbar, which still exceeds the pressure range relevant for studies in vivo in micro-organisms, including piezophilic bacteria from deep-sea environments.

Animals↗
PubMed2003

Assessing the benefit of biological valve prostheses: cumulative incidence (actual) vs. Kaplan-Meier (actuarial) analysis.

OBJECTIVE: The standard method of analysing structural valve degeneration (SVD) of biological prostheses is the Kaplan-Meier method. In order to assess SVD with regard to competing risks (e.g. death particularly in elderly patients) cumulative incidence (actual analysis) was compared to Kaplan-Meier (actuarial analysis). METHODS: We retrospectively analysed 257 patients older than 60 years, who underwent mitral valve replacement with different biological prostheses between 1974 and 2000. Reoperation-free survival was determined, both according to Kaplan-Meier and cumulative incidence analysis. RESULTS: For the total group of patients older than 60 years, the 10- and 15-year freedom from reoperation was 79+/-5 and 55+/-8%, respectively, according to Kaplan-Meier and 90+/-2 and 83+/-3% according to cumulative incidence analysis. For patients older than 65 years of age (n=170), Kaplan-Meier analysis revealed 85+/-7% freedom from reoperation at 10 years vs. 94+/-3% according to cumulative incidence analysis. For those between 60 and 65 years of age (n=87), Kaplan-Meier freedom from reoperation was 76+/-7% at 10 years and 48+/-9% at 15 years vs. 86+/-4 and 75+/-5% according to cumulative incidence analysis. CONCLUSIONS: Kaplan-Meier analysis overestimates the 10- and 15-year risk of SVD compared to cumulative incidence analysis, thus underestimating the benefit of biological valve replacement. Cumulative incidence analysis may lead to a more complete evaluation of risk and benefit and thus better patient management.

Aged↗
PubMed2003

Aspirin in episodic tension-type headache: placebo-controlled dose-ranging comparison with paracetamol.

Most people with episodic tension-type headache (TTH) treat themselves with over-the-counter analgesics. In the absence of clear evidence of dose-related efficacy of the two most commonly used analgesics, aspirin (acetylsalicylic acid) and paracetamol (acetaminophen), this study compared two doses of each with placebo. In a double-blind, double-dummy, randomized parallel-groups comparative trial, 638 consenting subjects aged 16-65 years with episodic TTH (but not migraine) by IHS criteria were recruited from the UK general population by advertisement. They treated one episode of moderate or severe TTH with a single dose of 500 or 1000 mg aspirin, 500 or 1000 mg paracetamol or placebo. The primary objective was to compare aspirin 1000 mg with placebo, and the primary end-point was subjective pain relief (total or worthwhile) 2 h after treatment ('response'). Additionally, pain intensity on a 100-mm visual analogue scale and functional impairment were monitored regularly for 4 h and at 24 h, although rescue medication was allowed after 2 h. The analysis was of the intention-to-treat population of 542 who took treatment (all providing outcome data). Treatment groups were matched at baseline. Aspirin 1000 mg (75.7% response rate; P = 0.0009) and to a lesser extent aspirin 500 mg (70.3%; P = 0.011) and paracetamol 1000 mg (71.2%; P = 0.007), but not paracetamol 500 mg (63.8%; P = 0.104), were statistically more effective than placebo despite a high placebo-response rate (54.5%). Outcome was not affected by headache intensity at baseline. Secondary end-points including functional recovery (by median times of 4.0-13.5 h) were consistent with these findings, although a minority of subjects recorded long-duration functional impairment (37-54 h). Adverse events reported by 13.4-18.9% of subjects were mild or moderate, and transient. No safety concerns arose.

Acetaminophen↗
PubMed2003

[Ultrasound imaging of the lower urinary tract in women before and after colposuspension: a 6-month follow-up].

OBJECTIVE: To evaluate the position of the bladder neck before and after open Burch colposuspension, using introital ultrasound. DESIGN: Retrospective longitudinal study using pre- and post-operative sonographic assessment of the position and function of the bladder neck. SETTING: Urogynecology units at the universities of Marburg/Göttingen and Witten/Herdecke and the DRK district hospital in Alzey, Germany. PATIENTS: 310 women undergoing open Burch colposuspension for primary genuine stress incontinence between September 1992 and December 2001. METHOD: Two-dimensional introitus sonography of the bladder neck prior to, one week and six months after surgery. RESULTS: The median age at surgery was 55 years (26 - 85). Open colposuspension lead to a 90.0 % (279/310) cure rate at 6 months with only 3.5 % (11/310) of the patients showing persistent micturation problems. A further 11.6 % (36/310) had symptoms of urgency and in 7 patients (2.3 %) a de novo urge-incontinence occurred. Post-operative bladder neck angles and movements at rest and during valsalva manoeuvre were significantly reduced while the resting bladder neck position was significantly elevated (p < 0.0001). Anatomical elevation of the bladder neck after open colposuspension varied between 2 - 39 with a median of 14.3 mm of neck elevation after one week and 9.9 mm at 6 month, respectively. Incontinence surgery lead to a significant reduction of the urethral funneling (p < 0.0001). CONCLUSION: In our series, open Burch colposuspension decreased both the bladder neck angle and the linear movement at rest and on valsalva as a result of the surgically stabilized bladder neck. Thus, our results support the hammock hypothesis that even small changes in the position of neck position are sufficient to reverse incontinence. We believe that perioperative introitus sonography is a helpful tool for the clinical assessment and documentation of not only morphological but also functional changes of the female continence organ before and after open Burch colposuspension.

Colposcopy↗
PubMed2003

[Stereolithography as an additive technique in dentistry].

3D-CAD constructions offer the application of CAM-techniques for the fabrication of dental restorations. CNC-units are generally used for milling and grinding. However, the application of new additive working technology enables the construction of 3D-solid models. In the field of rapid prototyping (RP), the process of "three-dimensional printing" allows the fabrication of patterns for the lost-wax casting technique from materials such as wax or resin. This paper describes the use of a light-curing fluid resin in combination with a UV-light projection in means of stereolithography (SL). The presented CAM unit (Perfactory, DeltaMed, D-Friedberg) reduces processing times of large casting patterns by using CAD constructions. This concept focuses on the advancement of the common casting technique in dental technology by application of CAD/CAM technology.

Computer-Aided Design↗