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Biomedical subjects

F Neumann

Publications and source records attributed to F Neumann.

At least 19 recordsLinked to original sources
PubMed2005

Successful transplantation of peripheral blood stem cells mobilized by chemotherapy and a single dose of pegylated G-CSF in patients with multiple myeloma.

Following induction therapy and 4 g/m(2) cyclophosphamide, a single dose of 12 mg polyethyleneglycol-conjugated G-CSF (pegfilgrastim; n=12) or daily doses of unconjugated G-CSF (8.5 mug/kg/day) (n=12) were administered to myeloma patients. Pegfilgrastim was associated with an earlier leukocyte recovery (12 vs 14 days) and peripheral blood CD34+ cell peak (12 vs 15 days). The peripheral blood CD34+ cell peak was lower in the pegfilgrastim group (78 vs 111/mul). Following high-dose melphalan (200 mg/m(2)) and autografting, leukocyte and platelet reconstitution was similar in both groups and stable blood counts were observed 100 days post transplant. In summary, a single dose of pegfilgrastim after chemotherapy is capable of mobilizing a sufficient number of CD34+ cells for successful autografting with early engraftment and sustained hematological reconstitution in patients with myeloma. These data provide the basis for randomized studies evaluating the optimal dose and time of pegfilgrastim as well as long-term outcome in larger cohorts of patients.

Adult↗
PubMed2005

Cyclosporine A and mycophenolate mofetil vs cyclosporine A and methotrexate for graft-versus-host disease prophylaxis after stem cell transplantation from HLA-identical siblings.

The combination of Cyclosporin A (CSA) and Methotrexate (MTX) is considered to be the standard regimen for the prevention of graft-versus-host disease (GVHD) after stem cell transplantation (SCT) from HLA-identical siblings. Mycophenolate Mofetil (MMF) has been widely used for GVHD prophylaxis after nonmyeloablative SCT, but experience following myeloablative therapy is still limited. We retrospectively compared CSA/MTX and CSA/MMF in 93 patients (median age 35 years, range 17-59 years, male subjects 48, female subjects 45) with acute myeloid leukemia (n=33), myelodysplastic syndrome (MDS) (n=3), acute lymphoblastic leukemia (ALL) (n=20) or chronic myeloid leukemia (n=37) who received CSA/MMF (n=26) or CSA/MTX (n=67) as GVHD prophylaxis following high-dose therapy and allogeneic SCT from HLA-identical siblings. No statistically significant differences were found in overall survival, relapse rate, treatment-related mortality and acute or chronic GVHD. Time to myeloid recovery was significantly shorter in patients who received CSA/MMF. We conclude that the combination of CSA/MMF appears equivalent to CSA/MTX for GVHD prophylaxis in patients receiving conventional-intensity SCT from HLA-identical siblings.

Adolescent↗
PubMed2005

[The effect of the field strength on standardized MRI of the brain to demonstrate cranial nerves and vessels: a comparison of 1.5 and 3.0 Tesla].

PURPOSE: Comparison of MR images acquired as routine examinations at a field strength of 3.0 T and 1.5 T to determine whether and to which degree the image quality improves at the higher field strength of 3.0 T. MATERIALS AND METHODS: Routine MR images of 200 patients were examined retrospectively, with 100 images obtained at 1.5 T and 100 obtained at 3.0 T. The examinations were performed with a quadrature head coil and focused on the basal cisterns because of the abundance of small distinct structures in this region. We selected the T2-weighted 2D-FSE sequence in transverse direction for comparison. At both field strengths, the same section thickness of 5 mm and a matrix of 512 x 388 (FOV: 220 mm) were used. The quality of the images was evaluated with regard to depicting the cranial nerves N. III, V - X, the AICA and PICA. For comparison, image quality was rated with a score from 1 (well defined) to 5 (not depicted). RESULTS: A score of 1 was obtained in 46 % of the anatomic structures examined at 3.0 T and in only 9.2 % at 1.5 T. A score of 2 was given in 27.6 % of the anatomic structures at 3.0 T vs. 23.5 % at 1.5 T, a score of 3 in 17.2 % vs. 28.1 %, a score of 4 in 8.6 % vs. 28.7 %, and a score of 5 in 0.4 % vs. 10.3 %, respectively. The Mann-Whitney U test showed significance at p < 0.001 for the comparison of images at 1.5 and 3.0 Tesla. CONCLUSION: Routine magnetic resonance imaging using the same quadrature coil technique and similar acquisition times at 3.0 T and 1.5 T shows an improvement for T2-weighted images at the higher field strength.

Adolescent↗
PubMed2004

Transplantation of allogeneic CD34+-selected cells followed by early T-cell add-backs: favorable results in acute and chronic myeloid leukemia.

BACKGROUND: The aim of this study was to investigate preservation of anti-leukemic activity and protection from opportunistic infections after transplantation of allogeneic + cells in patients with hematologic malignancies and bad prognosis. Methods Thirty-three patients [median age 42 years, range 23-55 years, diagnosis AML/myelodysplastic syndrome (MDS) 14, ALL nine, CML seven and multiple myeloma (MM) three] received myeloablative conditioning followed by infusion of selected CD34+ cells from matched unrelated donors (31) or HLA-identical siblings (two). Early donor lymphocyte infusions (DLI; 0.5 and 1.0 x 10(6) CD3+ cells/kg) were given while patients were on immunosuppressive therapy. RESULTS: Ninety-seven per cent of patients engrafted and 24 of 29 patients surviving more than 30 days received at least one pre-emptive DLI. Three patients (10%) developed acute (a)GvHD (two grade I-II, one grade III-IV) spontaneously, and 16 patients (67%) developed aGvHD after DLI (12 grade I-II, four grade III-IV). Eight of 24 evaluable patients developed chronic (c)GvHD (33%, six limited, two extensive). After a median follow-up of 590 days (range 138-1610 days) 18 patients were alive (55%), 16 in complete remission (CR), one in hematologic and one in molecular relapse. Seven patients died after relapse (21%) and eight died from transplantation-related causes (24%). Patients with myeloid malignancies had a significantly better survival than patients with ALL or MM (74%+/-10 vs. 30%+/-13, P<0.05). DISCUSSION: Early pre-emptive low-dose DLI following transplantation of selected CD34+ cells from unrelated donors after myeloablative conditioning is feasible and effective without undue toxicity, especially in patients with myeloid malignancies.

Adult↗
PubMed2003

Tetramethylphosphonium fluoride: "naked" fluoride and phosphorane.

Me(4)PF was investigated in the solid state, in the gas phase, and in solutions. Vibrational spectra of the solid and a single-crystal structure show an ionic tetramethylphosphonium fluoride. The compound crystallizes in the space group Pbca with a = 1016.0(1), b = 1018.0(1), c = 1205.8(4) pm, and Z = 8. The fluoride ion is nearly trigonal planar surrounded by three Me(4)P+ cations forming six H...F contacts between 218 and 240 pm. The compound is stable below 120 degrees C and sublimes in a vacuum. It possesses a phosphorane structure in the gas phase that was studied by electron diffraction and vibrational spectra, and additionally by theoretical calculations. The Me(4)PF molecule has a trigonal bipyramidal structure with one methyl group and the fluorine atom in axial positions and bond lengths of d(PC(eq)) = 182.6(4) pm, d(PC(ax)) = 188.4(8) pm, and d(PF) = 175.3(6) pm. The compound is remarkably soluble in acetonitrile, water, and alcohols, and slightly soluble in benzene, dimethyl ether, and diethyl ether. The solutions were studied by (1)H, (13)C, (19)F, and (31)P NMR spectroscopy. The hygroscopic Me(4)PF forms a tetrahydrate which crystallizes in the space group I4(1)/a with a = 1106.1(1) pm, c = 816.3(1) pm, and Z = 4. The fluoride ion in Me(4)PF.4 H(2)O is surrounded by four water molecules. These units form a three-dimensional network in which the Me(4)P+ cations are embedded without any contacts.

Journal Article↗
PubMed2003

Predictors of falls in elderly people during rehabilitation after hip fracture--who is at risk of a second one?

BACKGROUND: A fall in old age is known as a common consequence of frailty and decline as well as a risk factor for further falls. Studies identifying hip fracture patients who are at risk of a further fall are lacking. Therefore it was of interest to evaluate the risk factors for falling in a high-risk population, i.e., patients during rehabilitation after recent proximal femur fracture. METHODS: 935 consecutive patients who had surgical intervention after acute fracture of the proximal femur underwent a multidimensional assessment within the first two days after admission to the rehabilitation ward. Falls during the stay on the rehabilitation ward were registered. The baseline data were compared between fallers and non-fallers. FINDINGS: 11.8% of the patients fell during rehabilitation. Risk factors associated with a fall were increasing age, male gender, type of surgery, the use of a rollator and nocturnal urinary incontinence. The risk of falling increased in the middle of the second week of rehabilitation, when frailer patients gained mobility and ability to walk by themselves, while they were not yet safe enough. INTERPRETATION: It was possible to compose a risk profile for future falls. Those identified as 'at risk of a further fall' should be selectively offered protective devices and special training programs in order to prevent future fractures. As for the surgical intervention, the type of surgery in relation to age and long-term outcome is of particular interest since the use of the more expensive total hip arthroplasty procedure may be more cost effective in the long term.

Accidental Falls↗
PubMed2003

[Methods of process management in radiology].

The main emphasis in health care has been on quality and availability but increasing cost pressure has made cost efficiency ever more relevant for nurses, technicians, and physicians. Within a hospital, the radiologist considerably influences the patient's length of stay through the availability of service and diagnostic information. Therefore, coordinating and timing radiologic examinations become increasingly more important. Physicians are not taught organizational management during their medical education and residency training, and the necessary expertise in economics is generally acquired through the literature or specialized courses. Beyond the medical service, the physicians are increasingly required to optimize their work flow according to economic factors. This review introduces various tools for process management and its application in radiology. By means of simple paper-based methods, the work flow of most processes can be analyzed. For more complex work flow, it is suggested to choose a method that allows for an exact qualitative and quantitative prediction of the effect of variations. This review introduces network planning technique and process simulation.

Cost-Benefit Analysis↗
PubMed2003

[Prospective cost-benefit analysis of a fully digitized working environment in an ultrasound division applying process simulation].

PURPOSE: Quantification of expected savings of work load and personnel costs after implementation of a digital infrastructure in an ultrasound division of a radiology department. MATERIALS AND METHODS: The work flow of an ultrasound examination was simulated by means of a computer model. After validation, the computer model was modified to represent a work flow with PACS, electronic patient record, and automatic scheduling. The simulation results of work load, equipment utilization, and personnel costs were compared for both scenarios. RESULTS: The total number of work steps was reduced from 29 in the conventional scenario to 14 work steps in the scenario with digital infrastructure. The work load of administrative activities decreased by 89 % whereas the work load of activities directly related to the ultrasound examination remained unchanged. The productive personnel costs declined from euro; 24 to euro; 16 per examination. The gross labor costs declined from euro; 33 to euro; 20 per examination. Given unchanged equipment and number of patients, the required number of physicians can be reduced from 3 to 2 and that of technicians from 2 to 1 by use of a digital infrastructure. CONCLUSION: A digital infrastructure possesses a great potential for efficiency provided that it is implemented comprehensively and the work flow is adapted utilizing the capabilities of automation in all work processes.

Automation↗
PubMed2001

Treatment of Chlamydia pneumoniae infection with roxithromycin and effect on neointima proliferation after coronary stent placement (ISAR-3): a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Vascular infection with Chlamydia pneumoniae might boost inflammatory responses that play a pivotal part in neointima formation, which is the main cause of restenosis after stenting. Our aim was to investigate whether or not treatment of C pneumoniae infection with antibiotics prevents restenosis after coronary stent placement. METHODS: We enrolled 1010 consecutive patients with successful coronary stenting into a randomised, double-blind trial. Patients received the macrolide antibiotic roxithromycin 300 mg once daily for 28 days (506), or placebo (504). Primary endpoint was frequency of restenosis (diameter stenosis >50%) at follow-up angiography, and secondary endpoint was rate of target vessel revascularisation during the year after stenting. A prespecified secondary analysis addressed treatment effect with respect to titre of C pneumoniae in serum. Analysis was by intention to treat. FINDINGS: Rate of angiographic restenosis was 31% (157 lesions) in the roxithromycin group and 29% (148) in the placebo group (relative risk 1.08 [95% CI 0.92-1.26]; p50.43), corresponding to a rate of target vessel revascularisation of 19% (120) and 17% (105), respectively (1.13 [0.95-1.36]; p50.30). The combined 1-year rates of death and myocardial infarction were 7% (36) in the roxithromycin group and 6% (30) in the placebo group (p50.45). We showed a significant interaction between treatment and C pneumoniae antibody titre (p50.038 for restenosis, p50.006 for revascularisation), favouring roxithromycin at high titres (adjusted odds ratios at a titre of 1/512 were 0.44 [0.19-1.06] and 0.32 [0.13-0.81], respectively). INTERPRETATION: Non-selective use of roxithromycin is inadequate for prevention of restenosis after coronary stenting. There is, however, a differential effect dependent on C pneumoniae titres. In patients with high titres, roxithromycin reduced the rate of restenosis.

Aged↗
PubMed2001

Transcriptome analysis reveals a role of interferon-gamma in human neointima formation.

The most effective immediate cure for coronary stenosis is stent-supported angioplasty. Restenosis due to neointima proliferation represents a major limitation. We investigated the expression of 2435 genes in atherectomy specimens and blood cells of patients with restenosis, normal coronary artery specimens, and cultured human smooth muscle cells (SMCs). Of the 223 differentially expressed genes, 37 genes indicated activation of interferon-gamma (IFN-gamma) signaling in neointimal SMCs. In cultured SMCs, IFN-gamma inhibited apoptosis. Genetic disruption of IFN-gamma signaling in a mouse model of restenosis significantly reduced the vascular proliferative response. Our data suggest an important role of IFN-gamma in the control of neointima proliferation.

Animals↗
PubMed2001

Treatment of severe steroid refractory acute graft-versus-host disease with infliximab, a chimeric human/mouse antiTNFalpha antibody.

Acute graft-versus-host disease (aGVHD) is a serious complication of allogeneic peripheral blood stem cell transplantation (PBSCT). Patients with severe aGVHD not responding to treatment with steroids have a poor prognosis. We treated four patients with severe aGVHD refractory to steroids with infliximab, a chimeric human/mouse antiTNFalpha antibody. Patients (CML 2, MM 1, AML 1) developed grade III-IV GVHD at a median of 34 days (range 15-76) after myeloablative PBSCT (two), donor lymphocyte infusion for relapsed CML (one) or non-myeloablative PBSCT (one), respectively. All patients had severe intestinal involvement in addition to skin and/or liver disease and had received treatment with high-dose steroids (four) for a median of 11 days (range 5-17) in addition to CsA (four) and MMF (three). Infliximab (10 mg/kg) was given once a week until clinical improvement. In three of four patients a complete resolution of diarrhea and significant improvement of skin and liver disease were observed. Two patients received one, one patient two and one patient three infliximab infusions. At present two patients are alive >200 days after therapy, one with limited cGVHD. Two patients died, one of progressive malignant disease without GVHD and one of refractory GVHD. Infliximab is apparently an active drug for the treatment of aGVHD.

Acute Disease↗
PubMed2000

Platelets induce alterations of chemotactic and adhesive properties of endothelial cells mediated through an interleukin-1-dependent mechanism. Implications for atherogenesis.

Platelets and alterations of chemotactic and adhesive properties of endothelium play an important role in the pathophysiology of atherosclerosis. We investigated the effect of platelets on secretion of monocyte chemotactic protein-1 (MCP-1) and on surface expression of intercellular adhesion molecule-1 (ICAM-1) of cultured endothelium. Pretreatment of cultured monolayers of endothelial cells with alpha-thrombin-activated platelets significantly enhanced secretion of MCP-1 and ICAM-1 surface expression (P<0.01) that could be inhibited by interleukin-1 (IL-1) antagonists by approximately 40%. Activation of transcription factor nuclear factor-kappaB (NF-kappaB) which regulates transcription of early inflammatory response genes such as MCP-1, was significantly increased in endothelial cells treated with activated platelets via an IL-1 mediated mechanism as determined by electrophoretic mobility shift assay (EMSA) and kappaB-dependent transcriptional activity. In trans-well experiments, alpha-thrombin-activated platelets enhanced IL-1-dependent surface expression of vitronectin receptor (alpha(v)beta(3)) on the luminal aspect of endothelial monolayers and promoted alpha(v)beta(3)-mediated platelet/endothelium adhesion that could be inhibited by the antiadhesive peptides GRGDSP and c(RGDfV). We conclude that activated platelets induce significant changes in chemotactic (secretion of MCP-1) and adhesive (surface expression of ICAM-1 and alpha(v)beta(3)) properties of cultured endothelium. These findings imply a potential pathophysiological mechanism of platelets in an early stage of atherogenesis.

Blood Platelets↗
PubMed2000

Staged growth of optimized arterial model trees.

There is a marked difference in the structure of the arterial tree between epi- and endocardial layers of the human heart. To model these structural variations, we developed an extension to the computational method of constrained constructive optimization (CCO). Within the framework of CCO, a model tree is represented as a dichotomously branching network of straight cylindrical tubes, with flow conditions governed by Poiseuille's law. The tree is grown by successively adding new terminal segments from randomly selected points within the perfusion volume while optimizing the geometric location and topological site of each new connection with respect to minimum intravascular volume. The proposed method of "staged growth" guides the generation of new terminal sites by means of an additional time-dependent boundary condition, thereby inducing a sequence of domains of vascular growth within the given perfusion volume. Model trees generated in this way are very similar to reality in their visual appearance and predict diameter ratios of parent and daughter segments, the distribution of symmetry, the transmural distribution of flow, the volume of large arteries, as well as the ratio of small arterial volume in subendocardial and subepicardial layers in good agreement with experimental data. From this study we conclude that the method of CCO combined with staged growth reproduces many characteristics of the different arterial branching patterns in the subendocardium and the subepicardium, which could not be obtained by applying the principle of minimum volume alone.

Algorithms↗
PubMed1999

Shear stress distribution in arterial tree models, generated by constrained constructive optimization.

Models of arterial trees are generated by the algorithm of Constrained Constructive Optimization (CCO). Straight cylindrical, binary branching tubes are arranged in an optimized fashion so as to convey blood to the terminal sites of the tree, which are distributed over a predefined area, representing the tissue to be perfused. All terminal segments supply equal flows at a unique terminal pressure, and the radii of parent and daughter segments are related via a bifurcation law. The connective structure and geometry of the model are optimized according to a target function such as total intravascular volume. The shear rate between blood and the vessel walls is computed in each segment and a new method is presented for rescaling a given CCO tree to a desired value of shear rate in the root segment. The effect of viscosity varying with shear rate is evaluated and a new method is presented for rescaling a CCO-tree segment by segment to consistent values of radii and variable viscosity. Shear stress is evaluated for its deviation from being proportional to shear rate and then subjected to various types of analyses. Usually both, shear stress and its variability, are found to be larger in the smaller than in the larger segments of the CCO-model trees. However, it is shown how the shear-stress distribution can be reshuffled between small and large segments when rescaling a CCO tree to obey a different bifurcation law, while its whole geometry remains unchanged and all boundary conditions remain fulfilled. The selection of optimization target is found to drastically affect shear-stress variability within bifurcations, which reaches a distinct minimum if the model is optimized according to intravascular volume. Finally, a rank-analysis of shear stress within each bifurcation shows that only two out of six possible rank patterns actually occur: the parent segment always experiences medium shear stress while minimum shear stress resides mostly in the larger, less frequently in the smaller daughter.

Arteries↗
PubMed1999

Pharmacokinetics of meropenem in critically ill patients with acute renal failure undergoing continuous venovenous hemofiltration.

OBJECTIVE: Meropenem is a broad-spectrum antibiotic used for severe infections. In patients with chronic end-stage renal failure, meropenem clearance is reduced and doses must be adjusted according to the creatinine clearance. The aim of this study was to assess pharmacokinetic data of meropenem in patients with acute renal failure and to determine the amount of drug removed by continuous venovenous hemofiltration, an often-used renal replacement therapy in patients with acute renal failure. METHODS: Nine critically ill anuric patients with acute renal failure undergoing continuous venovenous hemofiltration received 500 mg meropenem 2 or 3 times daily. Plasma and hemofiltrate concentrations were determined during 1 dosing interval at steady state. Pharmacokinetic parameters were calculated for a 2-compartment open model and dose requirements were calculated. RESULTS: The total meropenem clearance was 52.0 +/- 8.4 mL/min, with a hemofiltration clearance of 22.0 +/- 4.7 mL/min and a nonrenal-nonhemofiltration clearance of 29.9 +/- 5.4 mL/min; 235.9 +/- 88.6 mg, or 47.2% +/- 17.7%, of the dose were removed through continuous venovenous hemofiltration. The terminal elimination half-life was 8.7 +/- 3.5 hours and the volume of distribution at steady state was 12.4 +/- 1.8 L. Peak and trough concentrations for a dosing interval of 12 hours were 38.9 +/- 9.7 mg/L and 7.3 +/- 1.3 mg/L, respectively. The corresponding concentrations for a dosing interval of 8 hours were 44.7 +/- 10.4 mg/L and 11.9 +/- 0.7 mg/L, respectively. CONCLUSION: Pharmacokinetic data of anuric patients with acute renal failure were similar to those of patients with end-stage renal failure. Because hemofiltration contributes significantly to meropenem elimination, the recommended dose for critically ill anuric patients receiving continuous venovenous hemofiltration should be increased by 100% to avoid potential underdosing.

Acute Kidney Injury↗