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Biomedical subjects

M Glück

Publications and source records attributed to M Glück.

At least 19 recordsLinked to original sources
PubMed2005

Radiatively generated isospin violations in the nucleon and the NuTeV anomaly.

Predictions of isospin asymmetries of valence and sea distributions are presented which are generated by QED leading Oalpha photon bremsstrahlung effects. Together with isospin violations arising from nonperturbative hadronic sources (such as quark and target mass differences) as well as with even a conservative contribution from a strangeness asymmetry (s not equal to s), the discrepancy between the large NuTeV anomaly result for sin(2Theta(w)) and the world average of other measurements is removed.

Journal Article↗
PubMed2002

[Vertebral body stenting. A method for repositioning and augmenting vertebral compression fractures].

UNLABELLED: Purpose of the study was to demonstrate the effectiveness of expanding a fractured vertebral body by transpedicular dilatation and stenting. 7 human cadaveric vertebral bodies from L2 to L5 underwent axia compression until a vertebral burst fracture was provoked. Then, by bilateral transpedicular approach, balloon-catheters were introduced, which were armed with stents, usually used for angioplasty. The catheters were inflated with radiolucent fluid and the stents expanded under radiologic control. After expansion, the balloon was deflated and removed, the stents resting inside the vertebral body, holding their inflated shape. Then, the resulting hole was filled with an injectable biodegradable calcium-phosphate. CT-scans were performed after destruction and after expansion. Morphology before and after expansion was judged, using 3-D reconstructions. Vertebral body strength was measured before destruction and after treatment with an Instron testing machine. RESULTS: Vertebral body shape could be restored. Also impressed central parts of the bony endplate could be elevated by using a convergent approach through the pedicles. There was no collapse of the vertebral body after removing the catheter-balloons The vertebral body strength could be restored up to a physiologic level. This procedure gives new perspectives in the treatment either of osteoporotic compression or traumatic vertebral fracture. By using CT-guided technique, it could be performed by a minimally invasive approach percutaneously.

Aged↗
PubMed2001

Wannier-Stark states of a quantum particle in 2D lattices.

A simple method of calculating the Wannier-Stark resonances in 2D lattices is suggested. Using this method we calculate the complex Wannier-Stark spectrum for a nonseparable 2D potential realized in optical lattices and analyze its general structure. The dependence of the lifetime of Wannier-Stark states on the direction of the static field (relative to the crystallographic axis of the lattice) is briefly discussed.

Journal Article↗
PubMed2001

Non-Hermitian delocalization from Hermitian Hamiltonians.

Here we show that using Galilean transformations the non-Hermitian delocalization phenomenon, which is relevant in different fields, such as bacteria population (e.g., Bacillus subtilis), vortex pinning in superconductors, and stability solutions of hydrodynamical problems discovered by Hatano and Nelson [Phys. Rev. Lett. 77, 5706 (1996)], can be obtained from solutions of the time-dependent Schrödinger equation with a Hermitian Hamiltonian. Using our approach, one avoids the numerical complications and instabilities which result form the calculations of left and right eigenfunctions of the non-Hermitian Hamiltonian which are associated with the non-Hermitian delocalization phenomenon. One also avoids the need to replace the non-Hermitian Hamiltonian H by a supermatrix with twice the dimension of H, where the complex frequencies serve as variational parameters rather than eigenvalues of H.

Journal Article↗
PubMed2000

Clinical long-term follow-up results in intestinal neuronal dysplasia (IND).

Commonly available information on intestinal neuronal dysplasia (IND) is sparse. Especially well documented long-term courses are lacking. The aim of this study was to correlate defecation as a clinical parameter of the long-term course in malformations of the enteric nervous system with the morphological diagnosis. 57 children with intestinal neuronal dysplasia (IND) or aganglionosis with cranial intestinal dysganglionosis (agIND), diagnosed between 1983 and 1992, were analysed including histomorphological classification, collection of clinical data and evaluation of the defecation mode by questionnaire as a parameter of the long-term course. Of 29 dysganglionic (IND) patients, 9/29 cases (31 %) had been treated conservatively, 18/29 cases surgically (62.1%), in two children (6.9%) no therapy had been necessary. All 28 patients with Hirschsprung's disease and cranial IND (agIND) underwent resection. 46 of the children could be followed up 3.64 years after the end of the main therapeutic period and with a mean age of 6.7 years at the time of follow-up; 43.5% of the analysed children still showed severe constipation. 23.9% only were really cured; 15.2% had normal defecation still using conservative treatment and 17.4% had diarrhea. No significant difference was found between both groups, IND and agIND, and the results were independent of treatment modality. The results were much worse than in idiopathic constipation as reported in the literature and even worse in comparison to unselected Hirschsprung collectives. It has to be concluded that in IND with chronic constipation intensive long-term care is necessary and it is crucial that treatment algorithms should be outlined urgently together by pediatric gastroenterologists and pediatric surgeons. AgIND seems to need more extended resection following an exact histomorphological mapping by biopsies taken during enterostomy procedure.

Child↗
PubMed2000

Breast cancer progression and expression of blood group-related tumor-associated antigens.

There is sufficient evidence that blood group related Lewis antigens are tumor-associated molecules. We have conducted immunohistochemical analysis of the expression of Lewis antigens in breast cancer tissue as an indicator of the degree of malignancy and as a prognostic factor. The studies were performed by examining 43 female patients diagnosed with invasive ductal carcinoma of the breast. Postoperative specimens were stained immunohistochemically using a panel of monoclonal antibodies (MAbs) specific for tumor-associated antigens: sialosyl LewisA, LewisA, LewisB, Lewisx, and LewisY. The aims of the study were to compare the appearance of metastases, degree of cancer stage (pTNM), and its histologic differentiation with the expression of Lewis phenotype. The evaluation of antigen expression was performed quantitatively and independently by two pathologists. Statistical significance was defined by Mann-Whitney test. The presented analysis of Lewis antigens showed higher expression of LeB and LeA (p = 0.03) in patients in stage N2 than in stage N1. The expression of LeB and LeY was higher in patients in stage T4 than in stage T1 (p = 0.02). No differences were observed for histologic differentiation. These data suggest that the expression of sialosyl-LeA and LeB antigens in breast cancer may predict metastases to lymph nodes.

Antigens, Neoplasm↗
PubMed1999

Lifetime statistics for a Bloch particle in ac and dc fields.

We study the statistics of the Wigner delay time and resonance width for a Bloch particle in ac and dc fields in the regime of quantum chaos. It is shown that after appropriate rescaling the distributions of these quantities have a universal character predicted by the random matrix theory of chaotic scattering.

Journal Article↗
PubMed1995

DNA-damaging effect of cyclophosphamide on human blood cells in vivo and in vitro studied with the single-cell gel test (comet assay).

The single-cell gel (SCG) test was used to study the induction and persistence of DNA damage by cyclophosphamide (CP) in human blood cells after treatment in vitro and in vivo. S9-mix-activated CP (from 0.1 mM upward) induced DNA effects in a concentration-dependent manner in the in-vitro SCG test. Blood cells from various donors showed considerable intra- and interindividual variability. Incubation of CP-treated blood samples at 37 degrees C caused a rapid decrease in DNA effects, but DNA migration was still significantly increased 1 hr after the end of the CP treatment. Comparative studies with the in vitro sister chromatid exchange (SCE) test were performed that demonstrated that much lower CP concentrations (about 100 times) were required for a significant induction of SCEs. A group of 11 patients who suffered from vasculitis/collagen disease and were treated with low CP doses (50-200 mg/day) exhibited an elevated level of DNA damage in the SCG test with peripheral blood cells, compared with a group of 11 control persons or 5 patients without chemotherapy. Increases in DNA damage were variable and not clearly related to the CP dose. SCE tests could successfully be performed with 5 out of the 11 CP-treated patients; all showed significantly increased SCE frequencies. For six patients no result could be obtained with the SCE test due to a failure of lymphocyte proliferation. Three multiple sclerosis patients who received high doses of CP were investigated with the SCG test before, during, and after the treatment. The results indicate that CP-induced DNA effects that are detectable with the SCG test persist in vivo for a period of several days, but for less than 2 weeks. The results of our study provide information with regard to the use of the SCG test in human monitoring. The advantages and limitations of the test are discussed.

Adult↗
PubMed1993

Reactivity and intracellular location of the ACTH cell autoantigen in human fetal and adult anterior pituitary tissue.

Autoantibodies to anterior pituitary ACTH cells have been described in the sera from patients with Cushing's disease. We were here able to show that true ACTH cell autoantibodies do not react with the hormone itself or with Fc receptors in ACTH cells. They rather recognize a distinct pituitary cell-specific cytoplasmatic autoantigen located in a juxtanuclear position. ACTH cells from human adult pituitaries express Fc receptors producing a non-specific broad and diffuse cytoplasmic binding of normal immunoglobulins. After preparation of Fc-free F(ab)2 fractions from human immunoglobulins it could be demonstrated by immunohistochemical methods that human adult pituitary ACTH cells also contain the fetal ACTH cell autoantigen. However, Fc receptors, ACTH hormone or other proopiomelanocortin- (POMC-) derived fragments and the ACTH cell autoantigen are all located at distinct intracellular sites. ACTH cells in human fetal pituitaries were shown to lack Fc receptors. Thus, with this source of antigen the characteristic autoantibody pattern can be detected with undigested sera.

Adrenocorticotropic Hormone↗