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Biomedical subjects

S Schneider

Publications and source records attributed to S Schneider.

At least 73 records · Page 4Linked to original sources

[Direct MR arthrography of the wrist- value in detecting complete and partial defects of intrinsic ligaments and the TFCC in comparison with arthroscopy].

PURPOSE: To assess the value of two-compartment magnetic resonance (MR) wrist arthrography in comparison with diagnostic arthroscopy for the evaluation of defects of the triangular fibrocartilage complex (TFCC) and intrinsic ligaments in patients with refractory wrist pain. The direct MR arthrographies were evaluated following arthroscopic classification with consideration of complete and partial defects. The distinction between these types of lesions has clinical implications for treatment procedures such as cast immobilization, arthroscopic debridement, surgical repair or partial intercarpal arthrodesis. MATERIALS AND METHODS: Seventy-five patients (25 female, 50 males, mean age 38.3 years) who suffered from refractory wrist pain without radiography evidence of carpal instability underwent two-compartment wrist MR arthrography. Under aseptic conditions a solution of gadopentate dimeglumine and iodinated contrast agent (concentration 2.5 mmol/l) was injected into the radiocarpal and midcarpal joints under fluoroscopy guidance. Using a scanner of 1.5 T field strength and a wrist-coil following sequences were acquired: coronary and sagittal T (1)-weighted spin-echo (SE) sequences (TR 500 ms, TE 25 ms, matrix 512 x 512.3 mm) and coronary fast low angle shot (FLASH) 3D sequences (TR 24 ms, TE 11 ms, matrix 256 x 256, 1.5 mm, flip angle 50 degrees). All patients underwent subsequent arthroscopy of the wrist. The direct MR arthrographies were evaluated retrospectively by two observers experienced in the diagnosis of wrist pathology. They were not aware of the clinicial, arthrographic and arthroscopic findings. Pathology of the scapholunate ligament was classified according to the guidelines of the German Society of Hand Surgery (DGH), lesions of the lunotriquetral ligament according to Hempfling and lesions of the TFCC according to Palmer. RESULTS: Twenty-five complete and 47 partial defects were detected arthroscopically (TFCC: 21/20, scapholunate ligament: 3/18, lunotriquetral ligament: 1/9). The TFCC showed a higher prevalence for degenerative lesions (11 type 2C-lesions and 20 type 2A/B lesions) than for traumatic lesions (5 type 1A lesions, 5 type 1D lesions). For direct MR arthrography, the obtained sensitivities and specificities in assessing complete defects were 96 % and 99.6 % (T (1)-weighted SE) and 92 % and 100 % (FLASH 3D), respectively. For all partial defects, sensitivities and specificities were 68.1 % and 93.3 % (T (1)-weighted SE) and 63 % and 96.1 % (FLASH 3D), respectively. For depicting partial defects of the scapholunate ligament the T (1)-weighted SE sequence (83.3/95.5 %) was superior to the FLASH 3D sequence (64.7/96.6 %), p < 0.05. For the evaluation of the TFCC (T (1)-weighted SE: 65/94.4 %, FLASH 3D: 70/94.6 %) and the lunotriquetral ligament (T (1)-weighted SE: 44/89.4 %, FLASH 3D: 44 /96.7 %), direct MR arthrography showed an insufficient correlation with arthroscopy. CONCLUSION: Direct MR arthrography proved to be of equal value compared with diagnostic arthroscopy in detecting complete defects of the intrinsic ligaments and the TFCC. The method has the potential of replacing diagnostic arthroscopy for the evaluation of the intrinsic ligaments and the TFCC. The T (1)-weighted SE sequence appeared to be superior to the FLASH 3D sequence in evaluating partial defects of the scapholunate ligament. Direct MR arthrography did not reliably detect partial defects of the TFCC and the lunotriquetral ligament.

Adult↗

The short-term effects of fasting on the neuroendocrine system in patients with chronic pain syndromes.

It is commonly reported that short term fasting leads to mood enhancement and emotional harmonisation. We investigated psychosocial well-being and the neuroendocrine response, assessed by nightly urinary excretion of cortisol and catecholamines, in 28 inpatients with chronic pain syndromes during and after a one-week modified fast. Twenty-two of the patients (51.4 +/- 2.7 years, BMI 26.8 +/- 1.0 kg/m2) participated in a 7-day fast with daily intake of 300 kcal/day, six control patients (47.5 +/- 4.0 years; BMI 22.9 +/- 1.1 kg/m2) received a vegetarian-based diet. With fasting significant increases of the urinary concentration of noradrenaline (17.8 +/- 3.0-27.8 +/- 3.8 microg/ml), adrenaline (1.5 +/- 0.2-3.4 +/- 0.7 microg/ml) and cortisol (26.1 +/- 3.7-40.7 +/- 6.1 microg/ml) were observed, whereas controls showed no significant endocrine changes. The neuroendocrine response to fasting was pronounced in younger subjects (age <50 years) and in the presence of a BMI >25 kg/m2, moreover the increase in cortisol excretion was significantly higher in subjects with lower baseline cortisol levels. Mood and well-being increased non-significantly in both groups. Fasting was well tolerated, and regarded as beneficial by most fasting patients. Our results show that short-term fasting leads to neuroendocrine activation and may suggest that the extent of this response is dependent on the individual metabolic and endocrine state at baseline.

Affect↗

Relaxation and dephasing of multiexcitons in semiconductor quantum dots.

We measure the dephasing time of ground-state excitonic transitions in InGaAs quantum dots under electrical injection in the temperature range from 10 to 70 K. Electrical injection into the barrier region results in a pure dephasing of the excitonic transitions. Once the injected carriers fill the electronic ground state, the biexciton to exciton transition is probed and a correlation of the exciton and biexciton phonon scattering mechanisms is found. Additional filling of the excited states creates multiexcitons that show a fast dephasing due to population relaxation.

Journal Article↗

[Long-term follow-up of patients with acute myocardial infarction treated with primary angioplasty or thrombolysis. Results of the MITRA trial].

Long-term follow-up after treatment with primary angioplasty compared to treatment with thrombolysis in patients with acute myocardial infarction (AMI) remains still to be determined. We therefore analyzed the data of the "Maximal Individual Therapy" in Acute Myocardial Infarction (MITRA-1) Registry. Follow-up data for a median of 17 months after discharge were available in 2090 out of 2195 (95%) AMI patients treated with thrombolysis, as well as 293 out of 312 patients (94%) treated with primary angioplasty. There were only small differences in patient characteristics between the two treatment groups. Compared to patients treated with thrombolysis, those treated with primary angioplasty had a higher prevalence of prior myocardial infarction (16.4% versus 12.2%, p = 0.04), longer prehospital delay: 10 minutes (130 minutes versus 120 minutes, p = 0.002), and a longer door-to-treatment time: 45 minutes (p < 0.001). Primary angioplasty patients were more likely to be treated with beta-blockers (primary angioplasty 79.8% versus thrombolysis 66.2%, p < 0.001) or statins (24.5% versus 16.5%, p < 0.001). There was no difference between the treatment groups for total mortality (p = 0.90) nor for the combined endpoint of death or re-infarction (p = 0.85). However, the combined endpoint of death, re-infarction or percutaneous coronary intervention or coronary bypass surgery was significantly lower in the primary angioplasty group (primary angioplasty 25.6% versus thrombolysis 32.3%, univariate odds ratio 0.72, 95% CI: 0.55-0.95, p = 0.02). This result was confirmed by multivariate analysis after adjusting for confounding parameters (multivariate odds ratio: 0.62, 95% CI: 0.42-0.91). The beneficial effect of primary angioplasty compared to thrombolysis achieved during the hospital stay after an AMI is maintained during a 17 month follow-up. AMI patients treated with thrombolysis were more likely to be treated with either percutaneous coronary intervention or coronary bypass surgery after discharge.

Aged↗

A simulated annealing approach to define the genetic structure of populations.

We present a new approach for defining groups of populations that are geographically homogeneous and maximally differentiated from each other. As a by-product, it also leads to the identification of genetic barriers between these groups. The method is based on a simulated annealing procedure that aims to maximize the proportion of total genetic variance due to differences between groups of populations (spatial analysis of molecular variance; samova). Monte Carlo simulations were used to study the performance of our approach and, for comparison, the behaviour of the Monmonier algorithm, a procedure commonly used to identify zones of sharp genetic changes in a geographical area. Simulations showed that the samova algorithm indeed finds maximally differentiated groups, which do not always correspond to the simulated group structure in the presence of isolation by distance, especially when data from a single locus are available. In this case, the Monmonier algorithm seems slightly better at finding predefined genetic barriers, but can often lead to the definition of groups of populations not differentiated genetically. The samova algorithm was then applied to a set of European roe deer populations examined for their mitochondrial DNA (mtDNA) HVRI diversity. The inferred genetic structure seemed to confirm the hypothesis that some Italian populations were recently reintroduced from a Balkanic stock, as well as the differentiation of groups of populations possibly due to the postglacial recolonization of Europe or the action of a specific barrier to gene flow.

Algorithms↗

Prospective cross-sectional study of haemostatic factors in patients with and without coronary artery disease.

The role of haemostatic factors for arterial thrombosis, especially the prevalence of activated protein C (APC) resistance in patients with coronary artery disease (CAD), is controversial. Between November 1996 and August 1997, 665 patients were analyzed. Diagnosis of CAD was confirmed by coronary angiography, exclusion of CAD was accepted in the presence of negative stress testing or a negative coronary angiography. CAD was present in 370 (56%) and excluded in 295 (44%) patients. Patients with CAD were older (64 +/- 9.2 versus 57.7 +/- 16 years; P <or= 0.001), more often male [74.1 versus 48.5%; odds ratio (OR) = 3.0, 95% confidence interval (CI) = 2.2-4.2] and had a higher body mass index (27.2 +/- 3.6 versus 26 +/- 4.3; P <or= 0.001). Most conventional risk factors showed a higher prevalence in patients with CAD. An APC ratio < 2.0 showed a tendency towards a higher prevalence in patients with CAD (10.5 versus 6.4%; OR = 1.7, 95% CI = 1.0-3.0). This difference was significant in men (11.7 versus 4.2%; OR = 3.0, 95% CI = 1.3-7.1), but not in women (7.3 versus 8.6%; OR = 0.8, 95% CI = 0.3-2.2). Multiple logistic regression analysis showed an independent association of the presence of CAD with age, male gender, current smoking, arterial hypertension, lipoprotein(a) levels and an APC ratio < 2.0 (OR = 2.87, 95% CI = 1.08-8.12). APC resistance with an APC ratio < 2.0 was the only haemostatic factor that was independently associated with the presence of CAD. This association was significant only for men. It may indicate a contribution of the APC resistance to the development of CAD, which has to be proven by the follow-up.

Aged↗

T cell reactivity against the SmD1(83-119) C terminal peptide in patients with systemic lupus erythematosus.

BACKGROUND: The SmD1(83-119) peptide is a major target of the B cell response in patients with systemic lupus erythematosus (SLE). OBJECTIVE: To investigate the T cell response directed against this peptide, its disease specificity, and possible impact on SLE pathogenesis. METHODS: Peripheral blood mononuclear cells derived from 28 patients with SLE and 29 healthy and disease controls were stimulated by the SmD1(83-119) and the recombinant (r)SmD1 protein, and [3H]thymidine incorporation was measured. Patients with SLE were simultaneously tested for autoantibodies, disease activity, clinical symptoms, and medical treatments. RESULTS: T cell reactivity against the SmD1(83-119) peptide was detected in 11/28 (39%) patients with SLE and against the rSmD1 protein in 10/28 (36%) patients. In contrast, only 2/29 (7%) controls exhibited SmD1 reactivity. An analysis of proliferation kinetics showed that SmD1 reactive T cells are activated in vivo, as additionally confirmed by cytometric analysis. Addition of mammalian dsDNA to rSmD1 enhanced the rSmD1-specific T cell response. SmD1(83-119)-specific T cell reactivity was significantly more common in patients with cardiac and pulmonary symptoms. No correlation between T and B cell responses and disease activity was seen. CONCLUSION: SmD1(83-119) is a major T cell epitope of SmD1, commonly recognised by T cells from patients with SLE and much less commonly found by healthy or disease controls. This strong T cell reactivity as well as the high frequency and specificity of anti-SmD1(83-119) antibodies in SLE suggest a possible role in SLE pathogenesis, at least in a subset of patients.

Adult↗

Swelling of cross-linked polyelectrolyte gels.

A model of a cross-linked polyelectrolyte gel has been examined using Monte Carlo simulations. The simple model contained a charged defect-free network represented by linked charged beads and explicit counterions. Pressure-density relations for the polyelectrolyte gel, a corresponding non-ionic polymer gel, and several partly or fully degraded gels have been determined. The polyelectrolyte gel displayed a very large swelling capacity, in agreement with experiments. The swelling mechanism and chain properties are discussed and foundations of current theories on gel swelling are examined.

Journal Article↗

[Use of heparin in acute myocardial infarction in routine clinical practice in Germany. Results of the MITRA and MIR registries].

OBJECTIVE: Among other adjunctive medication, heparin is widely used in the therapy of acute myocardial infarction (AMI) today. Large randomized trials, however, have shown inconclusive data on the benefit of adjunctive heparin therapy for patients with AMI. The aim of this study was to describe the use of heparin and complication rates in routine clinical practice today. METHODS: MITRA and MIR were multicenter registries of AMI patients in Germany. During the years 1994 to 1998, 22,697 patients were registered with MITRA and MIR. Of these patients 49.9% received reperfusion therapy. RESULTS: 21,004 patients (92%) received heparin during acute therapy of AMI. The following factors were associated with withholding heparin: Bleeding at admission (OR 4.7; CI 3.2-6.8), cardiogenic shock (OR 1.8; CI 1.4-2.3) and fibrinolytic therapy with streptokinase (OR 2.1; CI 1.8-2.3). Complication rates of patients with heparin were only slightly higher than among those without heparin: 1.7% strokes and 1.9% bleedings were reported among the patients with fibrinolysis and heparin compared to 1.3% strokes and 1.4% bleedings among patients without heparin (p = ns). Mortality rates were 14.1% for patients with and 27.3% for patients without heparin (p < 0.001). CONCLUSIONS: Of the patients in MITRA and MIR 92% received heparin during AMI. Patients with active bleeding or in critical condition received heparin significantly less often. The selection of critically ill patients may have contributed to the high mortality of patients without heparin for AMI. Bleeding complication rates of patients with adjunctive heparin were only slightly higher than reported in randomized trials.

Adult↗

Ultralong dephasing time in InGaAs quantum dots.

We measure a dephasing time of several hundred picoseconds at low temperature in the ground-state transition of strongly confined InGaAs quantum dots, using a highly sensitive four-wave mixing technique. Between 7 and 100 K the polarization decay has two distinct components resulting in a non-Lorentzian line shape with a lifetime-limited zero-phonon line and a broadband from elastic exciton-acoustic phonon interactions.

Journal Article↗

Triamidoamine complexes of chromium(III) and chromium(IV).

Treatment of [CrCl3(THF)3] with slightly more than 1 equiv of Li3(N3N) [(N3N)(3-) = ((Me3SiNCH2CH2)3N)(3-)] affords the triamidoamine complex [Cr(N3N)] (1) in 75% yield. 1 is oxidized by PhICl2, CuCl2, or AgCl to give the chromium(IV) complex [Cr(N3N)Cl] (2) in moderate yields. Alternatively, complex 2 is obtained directly from [CrCl3(THF)3] in 50% yield after treatment with 0.5 equiv of Li3(N3N). Both compounds are high-spin complexes bearing three and two unpaired electrons, respectively. Their molecular structures are described revealing a trigonal monopyramidal and trigonal bipyramidal coordination geometry of the chromium center, respectively.

Journal Article↗

Primary angioplasty versus intravenous thrombolysis in acute myocardial infarction: can we define subgroups of patients benefiting most from primary angioplasty? Results from the pooled data of the Maximal Individual Therapy in Acute Myocardial Infarction Registry and the Myocardial Infarction Registry.

OBJECTIVES: We sought to determine the effectiveness of primary angioplasty compared with thrombolysis in clinical practice. BACKGROUND: In clinical practice, primary angioplasty for the treatment of acute myocardial infarction (AMI) has not yet been proven more effective than intravenous thrombolysis, nor have subgroups of patients been identified who would perhaps benefit from primary angioplasty. METHODS: The pooled data of two AMI registries--the Maximal Individual TheRapy in Acute myocardial infarction (MITRA) study and the Myocardial Infarction Registry (MIR)--were analyzed. A total of 9,906 lytic-eligible patients with AMI, with a pre-hospital delay of < or =12 h, were treated with either primary angioplasty (n = 1,327) or thrombolysis (n = 8,579). RESULTS: Despite differences in the patients' characteristics and concomitant diseases between the two groups, the prevalence of adverse risk factors was balanced. Univariate analysis of hospital mortality showed a more favorable course for patients treated with primary angioplasty: 6.4% versus 11.3% (odds ratio [OR] 0.54, 95% confidence interval [CI] 0.43 to 0.67). This was confirmed by logistic regression analysis (multivariate OR 0.58, 95% CI 0.44 to 0.77). Primary angioplasty was associated with a lower mortality in all subgroups analyzed. We observed a significant correlation between mortality and absolute risk reduction (r = 0.82, p < 0.0001) in the different subgroups: as mortality increased, there was an increase in absolute benefit of primary angioplasty compared with thrombolysis. CONCLUSIONS: These large registry data showed the effect of primary angioplasty to be more favorable than thrombolysis for the treatment of patients with AMI in clinical practice. This effect was not restricted to special subgroups of patients. As mortality increased, the absolute benefit of primary angioplasty also increased.

Aged↗

Incidence, determinants, and clinical course of reinfarction in-hospital after index acute myocardial infarction (results from the pooled data of the maximal individual therapy in acute myocardial infarction [MITRA], and the myocardial infarction registry [MIR]).

There are few data about the incidence, determinants, and clinical course of in-hospital repeat acute myocardial infarction (RE-AMI) after an index AMI. From June 1994 to June 1998, 22,613 patients with AMI as an index event were registered by the Maximal Individual Therapy in Acute Myocardial Infarction (MITRA) and Myocardial Infarction Registries (MIR). Of these, 1,071 (4.7%) had a RE-AMI. For the index event, 9,143 patients (40.5%) were treated with thrombolysis, 1,707 (7.5%) with primary angioplasty, and 443 (2.0%) with a combination of both. Multivariate analysis showed that previous AMI (odds ratio [OR] 1.59; 95% confidence intervals [CI] 1.35 to 1.86), age >70 years (OR 1.57; 95% CI 1.36 to 1.81), diagnostic first electrocardiogram (OR 1.37; 95% CI 1.19 to 1.59), and female gender (OR 1.14; 95% CI 1.05 to 1.32) were independently associated with a higher incidence of RE-AMI. The incidence of RE-AMI was higher when patients received thrombolysis (OR 1.36; 95% CI 1.15 to 1.61), and it was lower when they underwent primary angioplasty (OR 0.74; 95% CI 0.53 to 1.03) or received beta blockers (OR 0.84; 95% CI 0.72 to 0.97). Patients with RE-AMI had higher hospital mortality compared with those without RE-AMI (OR 4.35; 95% CI 3.83 to 4.95). Multivariate logistic regression analysis showed an independent association of RE-AMI with in-hospital death (OR 6.60; 95% CI 5.61 to 7.70), repeat revascularization (OR 2.91; 95% CI 2.42 to 3.50), low workload capacity on the bicycle ergometry test (OR 2.17; 95% CI 1.71 to 2.76), and ejection fraction <40% (OR 1.72; 95% CI 1.38 to 2.14) at discharge. Thus, RE-AMI occurs in 4.7% of patients after an AMI. Previous AMI, age >70 years, diagnostic first electrocardiogram, and female gender are independent determinants for RE-AMI. Thrombolysis is associated with a higher and beta blockers with a lower incidence of RE-AMI. Once a RE-AMI occurs, it is a strong predictor of in-hospital mortality and morbidity.

Adrenergic beta-Antagonists↗

[Quality assurance in acute myocardial infarct].

The Ludwigshafen myocardial infarction project has demonstrated, that an intense public media campaign can reduce prehospital delays in acute myocardial infarction. With an additional intrahospital improvement, this can lead to a better and more frequent use of recanalization (thrombolysis or percutaneous transluminal coronary angioplasty [PTCA]). Several large multicentric registries (60 minutes myocardial infarction project, MIR, MITRA) with a total of about 40,000 patients at over 300 hospitals in Germany showed, that intrahospital improvement of infarction therapy can also be achieved in other hospitals. Voluntary participation in an infarction registry leads to quality control and improvement. Two factors are especially important: (1) documentation of every infarction patient, and (2) documentation of the reasons why therapy was given or withheld in every single patient. The improvement in early therapy is associated with a 20% reduction of hospital mortality (MITRA-1). The media campaign in Ludwigshafen to reduce pre-hospital patient delay, however, could not yet be carried out in other areas effectively and intensely enough.

Adult↗

Functional domains of the yeast splicing factor Prp22p.

The essential Saccharomyces cerevisiae PRP22 gene encodes a 1145-amino acid DEXH box RNA helicase. Prp22p plays two roles during pre-mRNA splicing as follows: it is required for the second transesterification step and for the release of mature mRNA from the spliceosome. Whereas the step 2 function of Prp22p does not require ATP hydrolysis, spliceosome disassembly is dependent on the ATPase and helicase activities. Here we delineate a minimal functional domain, Prp22(262-1145), that suffices for the activity of Prp22p in vivo when expressed under the natural PRP22 promoter and for pre-mRNA splicing activity in vitro. The biologically active domain lacks an S1 motif (residues 177-256) that had been proposed to play a role in RNA binding by Prp22p. The deletion mutant Prp22(351-1145) can function in vivo when provided at a high gene dosage. We suggest that the segment from residues 262 to 350 enhances Prp22p function in vivo, presumably by targeting Prp22p to the spliceosome. We characterize an even smaller catalytic domain, Prp22(466-1145) that suffices for ATP hydrolysis, RNA binding, and RNA unwinding in vitro and for nuclear localization in vivo but cannot by itself support cell growth. However, the ATPase/helicase domain can function in vivo if the N-terminal region Prp22(1-480) is co-expressed in trans.

Adenosine Triphosphatases↗

Incidence, risk factors, and clinical outcome of stroke after acute myocardial infarction in clinical practice. MIR and MITRA Study Groups. Myocardial Infarction Registry. Maximal Individual Therapy in Acute Myocardial Infarction .

In this analysis of ischemic and hemorrhagic strokes after acute myocardial infarction (AMI) in 21,330 consecutively included patients with AMI, we found an incidence of stroke after AMI of 1.2% and a very poor prognosis. Previous stroke, atrial fibrillation, and older age were the strongest predictors of stroke after AMI; thrombolysis was a borderline risk factor and early therapy with aspirin was associated with a reduction in stroke after AMI.

Aged↗

The AN2 protein is a novel marker for the Schwann cell lineage expressed by immature and nonmyelinating Schwann cells.

The expression of the 330 kDa AN2 glycoprotein was studied in the rodent peripheral nervous system. AN2 is expressed by immature Schwann cells in vitro and in vivo and downregulated as the cells upregulate myelin genes. A subpopulation of nonmyelinating Schwann cells in the adult sciatic nerve retains expression of AN2. In rat sciatic nerve crushes, where Schwann cell numbers increase after initial axonal loss and markers of immature Schwann cells show an upregulation, no increased expression of AN2 was observed. In contrast, AN2 expression was upregulated in nerves from peripheral myelin protein-22-transgenic rats, where immature Schwann cells expand without axonal loss. Furthermore, coculture with neurons upregulated AN2 expression on Schwann cells in vitro. Polyclonal antibodies against AN2 inhibited the migration of an immortalized Schwann cell clone in an in vitro migration assay, and the purified AN2 protein was shown to be neither inhibitory nor permissive for outgrowing dorsal root ganglion neurites. AN2 is thus a novel marker for the Schwann cell lineage. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of purified AN2 from early postnatal mouse brain demonstrated that AN2 is the murine homolog of the rat NG2 proteoglycan.

Animals↗