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Biomedical subjects

M Niemeyer

Publications and source records attributed to M Niemeyer.

10 recordsLinked to original sources
PubMed2007

[Intravitreal bevacizumab for recurring choroidal neovascularisation].

We administered bevacizumab intravitreally to treat a recurrence of CNV after confocal laser coagulation and photodynamic therapy in a 32-year-old female patient with a single functional eye. Before and after treatment the vision in the affected eye was stable at 1.0. Before administration of the VEGF antibody leakage was distinctly seen on fluorescein angiography, which did not appear on examination after the treatment. Despite the entailed measure of risk we decided in favour of intravitreal application because it seemed promising in view of earlier positive clinical experience with it in exsudative AMD and macular oedema following central retinal vein occlusion. Intravitreal bevacizumab is an alternative that should also be considered for the treatment of idiopathic CNV. Careful clinical studies will follow.

Adult↗
PubMed2005

[The STEMMAT-project as part of health initiative BayernAktiv: adult stem cells from umbilical cord and cord blood as alternative to embryonic stem cell research].

Adult stem cells from umbilical cord and cord blood are an interesting alternative to embryonic stem cells because such research is commonly recognized as ethical undisputed and many aspects are still insufficiently investigated. In the context of the STEMMAT research project (STEM = Stem Cell and MAT = Material) different aspects of stem cells from umbilical cord and cord blood are investigated, to improve basic science understanding and potentially leading someday to a clinical application.

Cord Blood Stem Cell Transplantation↗
PubMed2005

[Private umbilical cord blood banking does not reduce the number of samples for scientific stem cell research].

OBJECTIVE: Private umbilical cord blood (UCB) banking after delivery has increased over the last decade. For adult/somatic stem cell research UCB is an essential source of stem cells and researchers question if the number of UCB samples for research might be reduced by private banking. METHODS: A survey among seven private blood banks in Germany and analysis and comparison of the number of UCB samples donated for research within the STEMMAT project with private blood banking were performed from 03/2003 to 06/2005 at the Frauenklinik (OB/GYN), Technical University Munich, Germany. RESULTS: Within 27.5 months 1,551 UCB samples were collected for research purposes; the effective recruitment rate was higher than expectations at an effective 66.2 %. Private UCB banking [n = 24] was distributed among three cord blood banks [n = 16, 6 and 4]. The rate of private blood banking was 0.99 % for all deliveries, thus reducing the effective rate for research purpose by only 1.5 %. CONCLUSION: Under the assumption of active and successful recruitment of scientific UCB samples, private blood banking does not significantly reduce this rate and therefore is a negligible rival in the competition for sufficient numbers of UCB samples for research.

Blood Banks↗
PubMed2004

[Umbilical cord stromal cells (UCSC). Cells featuring osteogenic differentiation potential].

The identification of appropriate cell types is necessary to establish cell-based therapies in regenerative medicine. These cell types must (1) be available in an appropriate amount, (2) be easy to obtain, (3) be sufficiently expandable in vitro, and (4) fit to or at least be able to differentiate into the required cell type. Since the umbilical cord is available without any intervention and represents a notable amount of tissue, we consider it to be a promising source for isolating cells for cell-based therapies. This study demonstrates that umbilical cord stromal cells (UCSC), the connective tissue cells of the umbilical cord, can be isolated in sufficient quantities and be well expanded. UCSC feature phenotypic plasticity and thus are functionally similar to stem cells. UCSC can be differentiated into cells with osteoblastic properties (expression of alkaline phosphatase, formation of bone nodules). It is concluded that the umbilical cord should no longer be regarded as valueless tissue and be unthinkingly discarded. Instead, it should be considered a valuable resource for the isolation of potent cells for cell-based therapies, especially for treatment of bone defects.

Alkaline Phosphatase↗
PubMed2003

Biocorrosion of magnesium alloys: a new principle in cardiovascular implant technology?

OBJECTIVES: To develop and test a new concept of the degradation kinetics of newly developed coronary stents consisting of magnesium alloys. METHODS: Design of a coronary stent prototype consisting of the non-commercial magnesium based alloy AE21 (containing 2% aluminium and 1% rare earths) with an expected 50% loss of mass within six months. Eleven domestic pigs underwent coronary implantation of 20 stents (overstretch injury). RESULTS: No stent caused major problems during implantation or showed signs of initial breakage in the histological evaluation. There were no thromboembolic events. Quantitative angiography at follow up showed a significant (p < 0.01) 40% loss of perfused lumen diameter between days 10 and 35, corresponding to neointima formation seen on histological analysis, and a 25% re-enlargement (p < 0.05) between days 35 and 56 caused by vascular remodelling (based on intravascular ultrasound) resulting from the loss of mechanical integrity of the stent. Inflammation (p < 0.001) and neointimal plaque area (p < 0.05) depended significantly on injury score. Planimetric degradation correlated with time (r = 0.67, p < 0.01). CONCLUSION: Vascular implants consisting of magnesium alloy degradable by biocorrosion seem to be a realistic alternative to permanent implants.

Absorbable Implants↗
PubMed2001

Does a hyperoncotic cardiopulmonary bypass prime affect extravascular lung water and cardiopulmonary function in patients undergoing coronary artery bypass surgery?

OBJECTIVE: Different types of colloidal priming for cardiopulmonary bypass (CPB) have been used to reduce fluid load and to avoid the fall of plasma colloid osmotic pressure (COP) that leads to edema formation and consequently can cause organ dysfunction. The discussion about the optimal priming composition, however, is still controversial. We investigated the effect of a hyperoncotic CPB-prime with hydroxyethyl starch (HES) 10% (200;0.5) on extravascular lung water (EVLW) and post-pump cardiac and pulmonary functions. METHODS: In 20 randomized patients undergoing elective coronary artery bypass graft surgery (CABG), a colloid prime (COP: 48 mmHg, HES-group, n = 10) and a crystalloid prime (Ringer's lactate, crystalloid group, n = 10) of equal volume were compared with respect to the effects on cardiopulmonary function. Cardiac index (CI), mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), systemic vascular resistance index (SVRI), pulmonary artery pressure (PAP), pulmonary vascular resistance index (PVRI), alveolo-arterial oxygen difference (AaDO(2)), pulmonary shunt fraction (Q(s)/Q(T)), EVLW (double-indicator dilution technique with ice-cold indocyanine green), COP, fluid balance and body weight were evaluated peri-operatively. RESULTS: Pre-operative demographic and clinical data, CPB-time, cross-clamp time and the number of anastomoses were comparable for both groups. During CPB, COP was reduced by 20% in the HES-group (18.9 +/- 3.7 vs. 23.7 +/- 2.2 mmHg, P < 0.05) while it was reduced by more than 50% of the pre-CPB value (9.8 +/- 2.0 vs. 21.4 +/- 2.1 mmHg, P < 0.05) in the crystalloid group (P < 0.05 HES- vs. crystalloid group). Post-CPB EVLW was unchanged in the HES-group but it was elevated by 22% in the crystalloid group (P < 0.05 HES- vs. crystalloid group), CI was higher in the HES-group (3.4 +/- 0.3 vs. 2.7 +/- 0.5l/min, P < 0.05). Fluid balance was less in the HES-group (813 +/- 619 vs. 2143 +/- 538, P < 0.05). Post-operative weight gain could be prevented in the HES-group but not in the crystalloid group (1.5 +/- 1.2 vs. -0.3 +/- 1.5, P < 0.05). No significant differences were seen for MAP, PAP, PCWP, SVRI, PVRI, AaDO(2) and (Q(s)/Q(T)) between the two groups at any time. CONCLUSIONS: Hyperoncotic CPB-prime using HES 10% improves CI and prevents EVLW accumulation in the early post-pump period, while pulmonary function is unchanged. This effect can be of benefit especially in patients with congestive heart failure.

Blood Loss, Surgical↗
PubMed1994

[AnaTü-MidroTutor. An interactive tutoral program for a microscopy course].

The AnaTü-MikroTutor is an interactive tutorial program providing specific information for the microscopic anatomical course. It is offered as additional tool during practical microscopy and can be used for recapitulation of histology. The software is based on MS-DOS and can be implemented on IBM compatible computers. The main menu imitates a microscopic desk with a microscope, folders for microscopic slides and written additional information to each slide. The various functions are activated by mouse click over the respective icons. The program is offered to the students parallel to the microscopic course at 4 workstations and at a single terminal at the microscopic hall during practical microscopy. The main body of the program contains digital images of the microscopic slides of the course of microscopy in Tübingen. Each slide is represented by an overview and up to six magnifications. Legends are available as overlay. In addition, textual information is offered to each slide, which is intended to initiate further studies, explain specific termini or to indicate clinical relevance.

Anatomy↗
PubMed1986

On the clinical value of thallium-201 washout analysis in the detection of multiple jeopardized myocardial regions.

In this study the relative importance of visual assessment and quantitative analysis myocardial stress perfusion scintigraphy in 72 patients with a 40% incidence of triple-vessel coronary disease was tested. The quantitative analysis of the uptake scintigram in combination with a washout rate study of thallium-201 was not superior to the visual analysis with regard to the overall detection of significant coronary disease (obstructions of at least 50%). The sensitivity of the quantitative analysis was 0.85 for the entire population and 0.90 for the triple-vessel disease group (specificity 0.90). Detection of jeopardized myocardial flow regions in patients with triple-vessel disease, however, resulted in a significantly better identification by quantitative analysis. Of the 87 jeopardized flow regions in the 29 patients with triple-vessel disease, 62 regions were detected by the quantitative analysis whereas 48 regions were noted by the visual evaluation. The post-test likelihood of this regional quantitative analysis with respect to the triple-vessel disease was 66%. The incidence of global ischemia as detected by washout abnormalities in cases with no or a maximum of one regional uptake defect was 7%.

Angina Pectoris↗