PubMed Health⌕ Search

Biomedical subjects

U Schumacher

Publications and source records attributed to U Schumacher.

At least 19 recordsLinked to original sources
PubMed2006

A novel interactive anatomic atlas of the hand.

Classical anatomic atlases cannot provide the spectrum of views and the detail required in modern diagnostic and surgical techniques. Computer modeling opens the possibility to choose any view from one single model. A computerized model of the hand is presented, which has been obtained by segmentation and graphic modeling of the Visible Human dataset. In addition to being able to choose arbitrary viewpoints, it allows interrogation of the chosen views by mouse click. We believe the functions of these new kinds of atlases are superior to the classical ones.

Anatomy, Artistic↗
PubMed2005

Computer-assisted screw insertion into the first sacral vertebra using a three-dimensional image intensifier: results of a controlled experimental investigation.

Currently there are few data available regarding the application and efficacy of computer-assisted procedures in the sacral spine. In order to optimize and standardize this procedure, a controlled experimental investigation has been performed. The aim of the study is to systematically assess the efficacy of a novel three-dimensional image intensifier used for navigated transiliac screw insertion into the first sacral vertebra. Screws were inserted iliosacrally into the first sacral vertebra of preserved human cadaver specimens. The instrument navigated procedure was performed with the "Siremobil Iso-C(3D) " (Siemens Medical Solutions) and the "Navigation System" by Stryker. The accuracy and quality of the imaging procedure as well as the fluoroscopic exposure times were measured. These results were compared to three control groups (CT-based navigation, C-arm navigation, and fluoroscopic guidance). In each group a total amount of 20 screws was implanted. Screw position was postoperatively assessed by Iso-C(3D) or CT-scan. The navigated procedure using the Iso-C(3D) provided good feasibility characteristics without requiring a specific matching process. It revealed the shortest procedure time of all navigated procedures and significantly decreased fluoroscopic time compared to C-arm navigation and fluoroscopic guidance. Furthermore, Iso-C(3D) navigation showed no screw malposition and was in this regard superior to C-arm navigated and fluoroscopic guided procedures. The quality of imaging was sufficient for accurate placement, but did not share the high-resolution level of CT-based navigation. These findings indicate that application of the Iso-C(3D) for navigated transiliac screw insertion into S1 can be recommended as a feasible and safe technique, enabling the surgeon to reduce procedure and fluoroscopic time. Further progress in improving the quality of the Iso-C(3D) image should be attempted.

Bone Screws↗
PubMed2005

Lectin histochemistry of the gastric mucosa in normal and Helicobacter pylori infected guinea-pigs.

Helicobacter pylori attaches via lectins, carbohydrate binding proteins, to the carbohydrate residues of gastric mucins. Guinea-pigs are a suitable model for a H. pylori infection and thus the carbohydrate composition of normal and H. pylori infected gastric mucosa was investigated by lectin histochemistry. The stomach of all infected animals showed signs of an active chronic gastritis in their mucosa, whereas no inflammation was present in the control animals. The corpus-fundus regions of the controls showed heterogeneous WGA, SNA-I, UEA-I and HPA binding in almost all parts of the gastric glands. While these lectins labelled the superficial mucous cells and chief cells heterogeneously, the staining of the parietal cells was limited to WGA and PHA-L. Mucous neck cells reacted heterogeneously with UEA-I, HPA, WGA and PHA-L. In the antrum, the superficial mucous cells and glands were stained by WGA, UEA-I, HPA, SNA-I or PHA-L. WGA, UEA-I, SNA-I and HPA labelled the surface lining cells strongly. The mucoid glands reacted heterogeneously with WGA, UEA-I, HPA, SNA-I and PHA-L. In both regions, the H. pylori infected animals showed similar lectin binding pattern as the controls. No significant differences in the lectin binding pattern and thus in the carbohydrate composition between normal and H. pylori infected mucosa could be detected, hence H. pylori does not induce any changes in the glycosylation of the mucosa of the guinea-pig. This unaltered glycosylation is of particular relevance for the sialic acid binding lectin SNA-I as H. pylori uses sialic acid binding adhesin for its attachment to the mucosa. As sialic acid binding sites are already expressed in the normal mucosa H. pylori can immediately attach via its sialic acid binding adhesin to the mucosa making the guinea-pig particularly useful as a model organism.

Animals↗
PubMed2005

Lectin histochemical investigations of the distal gut of chicks with special emphasis on the follicle-associated epithelium.

Carbohydrates on epithelial cell surfaces play an important role as attachment sites for different microorganisms like bacteria, viruses and protozoa. To obtain more information about the distribution of carbohydrates on the luminal surface along the intestine, lectin histochemical studies on different gut segments of chicks of different age groups were carried out using a panel of 13 lectins with specificities for Man, Glc, Gal, GalNAc, GlcNAc or GlcNAc oligosaccharides and Sia. Furthermore, we tried to find out whether previously reported specificities of certain lectins for M cells (membranous or multifold cells) in the bursa of Fabricius (BF) can be observed also on M cells of the intestine. As a result we were able to demonstrate binding of all lectins employed in these studies in all investigated gut segments. In some cases, the application of the same lectin led to varying staining intensities of the same histological structures in different age-groups (e.g. staining of the brush border with WGA, LEA, MAA or Conarva) or different gut segments (e.g. staining of goblet cells with CMA II, LEA and MPA). Hence, terminal carbohydrate residues of glycoconjugates on the intestinal epithelium vary depending on age and organ site. As glycoconjugates can act as attachment sites for microorganisms, these differences in the distribution of sugar residues may be one explanation for the site-specificity of certain pathogens. Furthermore, the binding of lectins to the follicle-associated epithelium (FAE) of the BF differs from that to the FAE of the intestine again stressing the site specificity of lectin binding. Thus, up to now no universal M-cell marker along the chicken intestine exists.

Animals↗
PubMed2005

Invasive pulmonary aspergillosis: frequency and meaning of the "hypodense sign" on unenhanced CT.

The purpose of this study was to establish the diagnostic value of central hypointensity ("hypodense sign") in lung consolidations or nodules, in severely immunocompromised or neutropenic patients, suspected of having invasive pulmonary aspergillosis (IPA), and to assess its recognition on unenhanced CT scans. Serial CT scans of the lung were retrospectively reviewed in 43 consecutive immunosuppressed patients with IPA, and assessed for the presence of the hypodense sign using standard mediastinal and lung windowing settings, as well as a special, narrower window setting (width 110-140 HU; level 15-40 HU). The temporal relationship between the occurrence of the first CT-finding suspicious of IPA and the appearance of the hypodense sign, as well as between this and the occurrence of the crescent sign, cavitation or reduction in lesion size, was evaluated. Additionally, CT-scans from 89 immunocompromised patients with viral (n=45) or bacterial (n=44) pneumonia, investigated in the same time period at our institution were reviewed, with respect to the presence of the "hypodense" sign. Unenhanced CT scans revealed the hypodense sign in 11 neutropenic patients and 2 severely immunocompromised patients, out of a total of 43 patients with IPA evaluated in this study (30.2%). The mean time between the appearance of the first CT-findings of IPA (large nodule or consolidation +/- positive halo sign) and the hypodense sign was 7.8 days, while the time interval between the hypodense sign and the occurrence of crescent sign, cavitation, or decrease of the lesion's size was 8.3 days. The hypodense sign did not occur in any of the patients with viral or bacterial pneumonia, in the control series. We consider the hypodense sign to be a supplementary tool in the diagnosis of IPA. Its sensitivity was low in our series, but the high specificity makes it valuable in predicting IPA, anticipating the occurrence of cavitation or crescent sign, which are considered specific, but late findings of IPA. The hypodense sign is recognizable also on unenhanced CT, when a narrower lung window setting is used.

Adolescent↗
PubMed2003

The effect of homeopathic plant extract solutions on the cell proliferation of human cutaneous fibroblasts in vitro.

BACKGROUND: According to homotoxicology illness is defined as an overload of the connective tissue matrix with toxic substances, the homotoxins. In order to support elimination of these homotoxins, complex homeopathic medicines were developed. Fibroblasts are the local cells of this matrix and produce and modulate the composition of the extracellular matrix (ECM) in every organ. OBJECTIVE: In this study, the effect of 17 potentiated plant extracts, which are components of some antihomotoxic remedies, on the cell proliferation of human cutaneous fibroblasts (F54) was analyzed as an indication of their influence on the ECM. MATERIAL AND METHODS: Cell proliferation of the F54 cells was measured by a colorimetric XTT-based assay kit. RESULTS: Six of the tested agents had no effect on the cell proliferation of fibroblasts; 11 plant extracts had a dose-dependent inhibitory effect on cell proliferation. CONCLUSIONS: As the modulation of the ECM is dependent on the activity of the fibroblasts, these results indicate that the plant extracts may modulate the composition of the ECM via the inhibitory effect on fibroblasts cell growth.

Cell Division↗
PubMed2001

Cell differentiation and chemotherapy influence p53 and Mdm2 immunoreactivity in human HT29 colon cancer cells grown in scid mice.

Absence of a functional p53 gene product can lead to increased p53 accumulation in cancer cells. In this contribution, the association between cell differentiation, chemotherapy and p53 immunoreactivity in human HT29 colon cancer cells grown in scid mice as undifferentiated cells and as mucin containing signet-ring cells was investigated. Mutated p53 was more frequently expressed in the undifferentiated tumour cells than in the signet-ring cells. 5-fluorouracil (5FU) treatment resulted in a substantial increase in the p53-positive signet-ring cell population (from 17% to 45%) and in an increased Mdm2 immunoreactivity. These findings indicate that mutated p53 expression is related to the differentiation pattern and that tumour cells devoid of mutated p53 immunoreactivity are preferentially eliminated by 5FU treatment.

Animals↗
PubMed2001

Lectin binding to cutaneous malignant melanoma: HPA is associated with metastasis formation.

Changes in protein glycosylation of tumour cells, as detected by lectin histochemistry, have been associated with metastasis formation in several human malignancies. This study analysed the association between lectin binding and metastasis in cutaneous malignant melanoma. In a 10-year retrospective study, sections of 100 primary cutaneous malignant melanomas were histochemically stained for the following 5 lectins: HPA, SNA-I, MAA, WGA and PHA-L, differing in their carbohydrate specificity. Since differences in the results of HPA binding depending on methodology have been reported, an indirect and a biotinylated method were employed for HPA. Kaplan-Meier analysis of time to first metastasis revealed a positive correlation between HPA binding and metastasis for both methods, with the biotinylated HPA method (P< 0.0001) being superior to the 'indirect' method (P = 0.0006). Cox regression analysis demonstrated that even after adjustment for stage, HPA positivity is an independent predictor for metastasis. The results of the present study indicate that N -acetyl-galactosamine/-glucosamine residues, recognized by HPA, are linked to metastasis in malignant melanoma. In contrast, beta1-6 branched oligosaccharides or sialic acid residues, both of which were correlated with metastasis in other malignancies, are of no functional importance for metastasis formation in malignant melanoma. Thus, HPA proved to be a useful and independent prognostic marker for the metastatic phenotype of melanoma.

Adult↗
PubMed2001

Helix pomatia agglutinin lectin-binding oligosaccharides of aggressive breast cancer.

Predicting long-term outcome after breast-cancer diagnosis remains problematic, particularly for patients with clinically small, axillary lymph node- negative tumours. Evidence suggests that the lectin Helix pomatia agglutinin (HPA) identifies oligosaccharides associated with poor-prognosis cancer. Our aim was to identify oligosaccharides that bind HPA in aggressive breast cancers. Breast-cancer cell lines (MCF-7, BT-549 and BT-20) and a cell line from human milk (HBL-100), which showed a range of HPA-binding intensities, were used to extract HPA-binding glycoproteins. Oligosaccharides were released using anhydrous hydrazine and separated on a range of HPLC matrices. We investigated whether HPA-binding oligosaccharides from cell lines were present in human breast-cancer tissues, using 69 breast-cancer specimens from patients with between 5 and 10 years' follow-up. A monosialylated oligosaccharide was over-expressed in the cell line that bound HPA strongly. Further analysis by normal-phase HPLC showed that the 2-aminobenzamide-conjugated oligosaccharide had a hydrodynamic volume of 4.58 glucose units (HPAgly1). Increased expression of HPAgly1 was associated with HPA staining of breast-cancer specimens (Student's t-test p = 0.025). Analysis of oligosaccharide levels and disease-free survival after treatment for breast cancer indicated a shorter disease-free interval for patients with elevated levels of HPAgly1. This is the first time that histochemical lectin staining has been correlated with biochemical mapping of oligosaccharides. Using this approach, we have identified a monosialylated HPA lectin-binding oligosaccharide present in breast-cancer cells grown in vitro which is elevated in breast-cancer specimens that bind the lectin.

Adult↗
PubMed2001

PAS-positive loops and networks as a prognostic indicator in cutaneous malignant melanoma.

Recently, microvascular channels, as detected by PAS histochemistry, were positively correlated with poor prognosis in uveal malignant melanoma. Since uveal melanomas are not penetrated by lymphatic vessels, while cutaneous melanomas are, the question arises as to whether these loops and networks are also of prognostic relevance in cutaneous melanoma. Histochemically and immunohistochemically detected loops and networks in 100 cases of cutaneous malignant melanoma were correlated with the occurrence of metastasis in a 10-year follow-up study. To detect these patterns, the significance of various methods (PAS reaction with/without nuclear counterstain, anti-laminin immunohistochemistry) was investigated. The presence of loops and networks was a highly significant prognostic marker (p<0.0001) for metastasis in cutaneous malignant melanoma. The presence of these patterns proved to have higher prognostic relevance for metastasis than Breslow's tumour thickness, especially for stage IB and stage IIA tumours (intermediate thickness/risk). PAS reaction without nuclear counterstain proved to be the best method to detect these patterns. Compared with the conventional staging of Breslow's tumour thickness, and especially so for stage IB and IIA melanomas, the determination of PAS-positive loops and networks in cutaneous malignant melanoma provides additional prognostic information.

Adult↗
PubMed2001

Carbohydrate expression in the intestinal mucosa.

UNLABELLED: The understanding of mechanisms responsible for alterations in mucin synthesis and secretions is essential in elucidating the aetiology of intestinal disorders. The existence of distinct mucins and M-cell transport mechanisms, and their beneficial effects, have long been recognised. Since nutritional and bacterial factors alter the mucin characteristics and are relevant to planning preventative strategies for intestinal diseases, the studies described in this monograph were designed to test the hypothesis that mucin composition and endocrine status of the intestinal tract are altered by dietary constituents and microbial flora. A study of gut-associated lymphoid tissue (GALT) was undertaken to test the hypothesis that lymphocyte-epithelial interactions influence the glycosylation of cells overlying Peyer's patches. The effects of diet and microbial flora were analysed by comparing the data from male Wistar germ-free rats, with conventional or human flora. Such rats were fed either a commercial diet, containing crude fibre, or a purified diet. Bone marrow transfers from syngeneic Balb/c mice to severe combined immunodeficient (SCID) mice were made to induce the formation of GALT. A comparison was made of the glycoconjugate profile of Peyer's patches in the guts of mice and humans. The results of the study showed that feeding a fibre-rich diet to germ-free rats resulted in increased villus-crypt lengths, decreased carboxylated mucin content of goblet cells, increased N-acetylglucosamine and sialic acid residues in the surface goblet cells, and a reduction in the number of endocrine cells in the small intestine. The lectin markers revealed M-cell development in the dome epithelium of the reconstituted SCID mice. Mouse M cells were labelled by fucose-specific lectins but in human Peyer's patches no distinct M-cell-staining pattern was observed. CONCLUSIONS: (1) the interactions between diet and flora alter the mucosal architecture and the activity of endocrine cells; (2) the dietary changes are influential in modifying the epithelial mucin predominantly in the small intestine while the microbial flora influences the mucosal architecture predominantly in the large intestine; (3) the use of bone marrow transplantation from syngeneic mice into SCID mice along with lectin markers for M cells can be used to study the histogenesis of Peyer's patches; (4) the distinct differences between mouse and human Peyer's patches suggest that when considering cell surface glycoconjugates as target molecules appropriate lectin should be used for each species. A future challenge in intestinal epithelial cell biology is identifying the nature and distribution of cell surface receptors for specific dietary components and bacteria.

Animals↗
PubMed2001

Status and problems of fusion reactor development.

Thermonuclear fusion of deuterium and tritium constitutes an enormous potential for a safe, environmentally compatible and sustainable energy supply. The fuel source is practically inexhaustible. Further, the safety prospects of a fusion reactor are quite favourable due to the inherently self-limiting fusion process, the limited radiologic toxicity and the passive cooling property. Among a small number of approaches, the concept of toroidal magnetic confinement of fusion plasmas has achieved most impressive scientific and technical progress towards energy release by thermonuclear burn of deuterium-tritium fuels. The status of thermonuclear fusion research activity world-wide is reviewed and present solutions to the complicated physical and technological problems are presented. These problems comprise plasma heating, confinement and exhaust of energy and particles, plasma stability, alpha particle heating, fusion reactor materials, reactor safety and environmental compatibility. The results and the high scientific level of this international research activity provide a sound basis for the realisation of the International Thermonuclear Experimental Reactor (ITER), whose goal is to demonstrate the scientific and technological feasibility of a fusion energy source for peaceful purposes.

Deuterium↗
PubMed2001

The corynebacterial flora of the normal human conjunctiva is lipophilic.

Corynebacterial isolates, obtained by selective and non-selective media from conjunctival swabs, were speciated by using two recently developed systems. All 25 strains from 92 individuals, as well as 12 strains from a previous similar study, belonged to lipophilic species. The significance of this unusual finding is discussed.

Adult↗
PubMed2001

Lectin histochemistry of microvascular endothelium in chick and quail musculature.

The lectin binding pattern of muscular microvessels in chick, quail and chick/quail chimeras was analysed. Paraffin wax sections of muscles from embryonic and adult animals were used. The biotin-labelled lectins were detected by avidin-alkaline phosphatase complex. The following lectins bound to muscular microvessels including arterioles, capillaries and venules of both species: SNA-I (Sambucus nigra agglutinin), MAA (Maackia amurensis agglutinin), AIA (Artocarpus integrifolia agglutinin), VAA-I, VAA-II and VAA-III (Viscum album agglutinin I-III), WGA (wheat germ agglutinin), LEA (Lycopersicon esculentum agglutinin). Endomysium and basement membranes of muscle fibres were also stained to a variable extent and intensity. Only SNA-I stained almost exclusively the endothelium of blood vessels. WFA (Wisteria floribunda agglutinin) bound to the quail endothelium only. MPA (Maclura pomifera agglutinin) marked vessels in adult muscles of chick and quail, but embryonic vessels were stained in quail only. Our results show that lectin histochemistry is a useful tool for visualisation of microvasculature in avian species. In particular, WFA and MPA can be used to determine the origin of endothelia in chick/quail chimeras.

Animals↗
PubMed2001

cis Interaction of the cell adhesion molecule CEACAM1 with integrin beta(3).

CEACAM1 is a cell adhesion molecule that has been implicated in a number of physiological processes (eg, tumor suppressor in epithelial tissues, potent angiogenic factor in microvessel formation, microbial receptor in human granulocytes and epithelial cells). The mechanism of CEACAM1 action is still largely unresolved but recent findings demonstrated that the cytoplasmic CEACAM1 domain is linked indirectly to the actin-based cytoskeleton. We have isolated integrin beta(3) as an associated protein using CEACAM1 tail affinity purification. This association depends on phosphorylation of Tyr-488 in the CEACAM1 cytoplasmic domain. Confocal laser scanning microscopy confirmed in vivo colocalization of both molecules in human granulocytes and epithelial cells. Furthermore, the concentrated colocalization at the tumor-stroma interface of invading melanoma masses suggests a functional role of CEACAM1-integrin beta(3) interaction in melanoma invasion. Moreover, colocalization of the two adhesion molecules is also found at the apical surface of glandular cells of pregnancy endometrium. Colocalization of CEACAM1 and integrin beta(3) at the transitional zone from proliferative to invasive extravillous trophoblast of the maternal-fetal interface supports a role for CEACAM1/integrin beta(3) complexes in cell invasion.

Antigens, CD↗
PubMed2001

Creating a high-resolution spatial/symbolic model of the inner organs based on the Visible Human.

Computerized three-dimensional models of the human body, based on the Visible Human Project of the National Library of Medicine, so far do not reflect the rich anatomical detail of the original cross-sectional images. In this paper, a spatial/symbolic model of the inner organs is developed, which is based on more than 1000 cryosections and congruent fresh and frozen CT images of the male Visible Human. The spatial description is created using color-space segmentation, graphic modeling, and a matched volume visualization with subvoxel resolution. It is linked to a symbolic knowledge base, providing an ontology of anatomical terms. With over 650 three-dimensional anatomical constituents, this model offers an unsurpassed photorealistic presentation and level of detail. A three-dimensional atlas of anatomy and radiology based on this model is available as a PC-based program.

Anatomy, Cross-Sectional↗
PubMed2001

Fetuin in human bone marrow: detection in foetal tissue and patients with mastocytosis.

Fetuin, a foetal protein of unknown function, has been shown to be expressed in both the immune and nervous systems, especially during development. Here, we show for the first time, that fetuin is abundantly present in many cells of the foetal human bone marrow, but is restricted to cells of the monocytic lineage in the adult. Fetuin's immunoreactivity increased considerably in adult human bone marrow in some pathological conditions, particularly in mastocytosis and was also increased in bone marrows in some cases of acute leukaemias, especially in acute myeloid leukaemia. This increase in the presence of fetuin in neoplastic bone marrows is not reflected by an increased level of circulating fetuin. This last observation contradicts earlier suggestions that fetuin is specifically reduced in cancer patients. A consistent increase in fetuin immunoreactivity in bone marrow of most cases of mastocytosis, as demonstrated in this paper, could become a useful tool in the diagnosis of this disease.

Adult↗