Search PubMed⌕ Search

Biomedical subjects

H Baumann

Publications and source records attributed to H Baumann.

At least 19 recordsLinked to original sources
PubMed2006

Effect of exercise, body composition, and nutritional intake on bone parameters in male elite rock climbers.

A low body mass index is considered essential for high performance in rock climbing; however its effect on bone may be negative. In this study we compared the BMD of competitive male rock climbers (n = 20) and age- and BMI-matched non-training controls (n = 11). Subjects with any medication or illness affecting bone metabolism or a family history of osteoporosis were not included in the analysis. Total body BMD was measured by dual-energy X-ray absorptiometry. Quantitative computed tomographic scans were made from the femoral neck and the lumbar spine. Dietary intake was assessed by a 5-day protocol. BMD of the TB-scan was significantly higher in the climbers group for all sub-regions except the skull (p = 0.191) and the lower extremities (p = 0.079). Trabecular and cortical BMD of the LS were significantly higher (p = 0.036 and p = 0.004) in the climbers. The same was true for total (p = 0.005) and cortical (p = 0.002) BMD of the FN. Trabecular BMD (p = 0.054), CSA (p < 0.343) and cortical thickness (p = 0.065) of the FN was non-significantly higher for the climbers. Our study indicates that the effect of climbing on bone parameters PER SE is not detrimental in elite male athletes. Contrarily climbers demonstrated significantly higher BMD values at all loaded regions without "steal effects" at skeletal sites with low mechanical impact. Although we determined a moderately negative effect of low BMI on BMD we could not decide whether a low BMI value should be used as an exclusion criterion in high level climbing competitions as practized by the Austrian Sportclimbing Organization.

Absorptiometry, Photon↗
PubMed2004

Impact of disease activity on thyroid diseases in patients with acromegaly: basal evaluation and follow-up.

In patients with acromegaly, the exact incidence of thyroid disorders is still controversial and less is known about the impact of disease activity and successful treatment. To address this issue, we investigated 73 acromegalic patients (age 55 +/- 13 yr; mean +/- SD) by ultrasonography in comparison to an age-matched control group (54 +/- 1 yr) in the same moderate iodine deficient area (retrospective study). These non-acromegalic volunteers (n = 199) were examined in the same clinic during a thyroid screening test. At the time of examination, 52 (71.2 %) of the acromegalic patients were active, 17 (23.3 %) were cured, and 4 (5.5 %) were controlled with somatostatin analogues. The prevalence of goiter (normal range < 18 ml female, < 25 ml male) was significantly higher (82.2 %) in the mixed group of acromegalics (active, well controlled, cured; n = 73) and in the active group (90.4 %) than in the control group (n = 199, 18.1 %, p < 0.001). Thyroid nodules were found in 63.0 % of the mixed group of acromegalics and in 71.2 % of patients with active disease (33.1 % in controls, p < 0.001). (99 m)Tc scintigraphy revealed thyroid autonomy in 9/73 (12.3 %) and cold nodules in 19/73 (26.0 %) patients. Thyroid cancer was diagnosed in 4 (5.5 %) of acromegalic patients (3 papillary and 1 follicular carcinoma). We found a weak correlation between the disease duration and the initial thyroid volume (r = 0.54, p < 0.0056). Thirty-seven newly diagnosed acromegalics were followed over a period of 7.3 +/- 4.1 years. 5 (13.5 %) of these patients remained active, 8 (21.6 %) were controlled with somatostatin analogues, and 24 (64.9 %) were cured. The mean age, sex distribution, disease duration, prevalence of TSH-deficiency, and initial thyroid volume (46 +/- 11 ml in active, 42 +/- 7 ml in controlled, and 45 +/- 5 ml in cured patients) did not differ statistically between the three groups. In patients with active acromegaly, thyroid volume increased by 19.5 +/- 8.1 %. In contrast, thyroid volume decreased in the group of medically controlled and cured acromegalics (- 21.5 +/- 7.1 %; p < 0.005 and - 24.2 +/- 5.7 %; p < 0.002, respectively). No correlation was found between thyroid volume and TSH levels, levothyroxine and/or iodide administration neither in TSH sufficient nor in TSH insufficient patients. In conclusion, successful treatment of patients with active acromegaly decreases thyroid volume. Cold nodules and thyroid cancer frequently occur in acromegalic patients.

Acromegaly↗
PubMed2003

Role of cytokines in photodynamic therapy-induced local and systemic inflammation.

Photodynamic therapy (PDT) of tumour results in the rapid induction of an inflammatory response that is considered important for the activation of antitumour immunity, but may be detrimental if excessive. The response is characterised by the infiltration of leucocytes, predominantly neutrophils, into the treated tumour. Several preclinical studies have suggested that suppression of long-term tumour growth following PDT using Photofrin((R)) is dependent upon the presence of neutrophils. The inflammatory pathways leading to the PDT-induced neutrophil migration into the treated tumour are unknown. In the following study, we examined, in mice, the ability of PDT using the second-generation photosensitiser 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH) to induce proinflammatory cytokines and chemokines, as well as adhesion molecules, known to be involved in neutrophil migration. We also examined the role that these mediators play in PDT-induced neutrophil migration. Our studies show that HPPH-PDT induced neutrophil migration into the treated tumour, which was associated with a transient, local increase in the expression of the chemokines macrophage inflammatory protein (MIP)-2 and KC. A similar increase was detected in functional expression of adhesion molecules, that is, E-selectin and intracellular adhesion molecule (ICAM)-1, and both local and systemic expression of interleukin (IL)-6 was detected. The kinetics of neutrophil immigration mirrored those observed for the enhanced production of chemokines, IL-6 and adhesion molecules. Subsequent studies showed that PDT-induced neutrophil recruitment is dependent upon the presence of MIP-2 and E-selectin, but not on IL-6 or KC. These results demonstrate a PDT-induced inflammatory response similar to, but less severe than obtained with Photofrin((R)) PDT. They also lay the mechanistic groundwork for further ongoing studies that attempt to optimise PDT through the modulation of the critical inflammatory mediators.

Animals↗
PubMed2003

Haptoglobin directly affects T cells and suppresses T helper cell type 2 cytokine release.

T helper cell type 1 (Th1) and type 2 (Th2) immune responses are characterized by a different pattern of cytokine expression following T-cell activation. Alterations of the ratio of Th1 to Th2 cells are important determinants of susceptibility to viral and parasitic infections, allergies, anti-tumour responses, and autoimmunity. In this work we bring new evidence for an effect of haptoglobin (Hp), a positive acute-phase protein, on T-lymphocyte functions. We show that Hp specifically interacts with both resting and activated CD4+ and CD8+ T cells. This specific binding results in a strong suppression of induced T-cell proliferation. In addition, Hp exhibits a strong in vitro inhibitory effect on Th2 cytokine release, while the production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) is only slightly inhibited at high Hp doses. As a result, the presence of Hp promotes Th1 activation over Th2 activation in vivo as evidenced in Hp-deficient mice. Anti-CD3 monoclonal antibody injection indeed resulted in predominant IL-4 production in Hp-/- mice, in contrast to predominant IFN-gamma production in Hp+/+ mice. We conclude that Hp plays a modulating role on the Th1/Th2 balance by promoting a dominant Th1 cellular response. This points to a role of acute-phase proteins in balancing immune responses.

Adjuvants, Immunologic↗
PubMed2002

Diffusion studies in non-oxide ceramics: analytical aspects of the use of ion implanted stable tracers and SIMS.

The physical and chemical properties of complex non-oxide ceramic materials require advanced methods of diffusivity determination. In this study, we present a method based on the high-dose ion implantation of stable tracers in combination with secondary ion mass spectroscopy for depth profiling. The analytical basics, advantages and problems of the method are discussed for two examples of complex materials, the Si-B-C-N precursor ceramics and the Ti-based transition metal diborides. We demonstrate that is possible to measure the temperature dependence of diffusivities, especially for ceramic systems with low diffusivities, for systems that contain elements for which no suitable radioactive tracers exist for extended measurements.

Ceramics↗
PubMed2002

Phylogeny and geographical differentiation of zucchini yellow mosaic virus isolates (Potyviridae) based on molecular analysis of the coat protein and part of the cytoplasmic inclusion protein genes.

DNA sequences for the coat protein (CP) and part of the cytoplasmic inclusion (CI) protein genes after reverse transcriptase-polymerase chain reaction (RT-PCR) were reported for the first time for isolates of zucchini yellow mosaic virus (ZYMV) from Austria, Germany, Italy and Slovenia. Comparison of the DNA sequences of 30 isolates from different geographical regions worldwide revealed highest similarities of the Austrian isolates to those from Slovenia and Hungary. Isolates from Germany and Italy were only distantly related and clustered with isolates from other parts of the world. Our results indicate that a specific isolate can spread rapidly to geographically adjacent areas but may not be directly related to isolates found in other neighboring countries.

Capsid↗
PubMed2002

Overexpression of alpha(1)-acid glycoprotein in transgenic mice leads to sensitisation to acute colitis.

BACKGROUND: alpha(1)-Acid glycoprotein (alpha(1)-AGP) is an acute phase protein in most mammalian species whose concentration rises 2-5-fold during an acute phase reaction. Its serum concentration has often been used as a marker of disease, including inflammatory bowel disease (IBD). High alpha(1)-AGP levels were found to have a prognostic value for an increased risk of relapse in IBD. AIMS: To investigate a possible role for increased serum levels of alpha(1)-AGP in the development of IBD. METHODS: Dextran sodium sulphate (DSS) 2% was added to the drinking water of transgenic mice, overexpressing the rat alpha(1)-AGP gene, to induce acute colitis, thus mimicking the conditions of relapse. Clinical parameters, inflammatory parameters, and histological analyses on colon sections were performed. RESULTS: Homozygous alpha(1)-AGP-transgenic mice started losing weight and showed rectal bleeding significantly earlier than heterozygous transgenic or wild-type mice. Survival time of homozygous transgenic mice was significantly shorter compared with heterozygous and wild-type mice. The higher susceptibility of homozygous alpha(1)-AGP-transgenic mice to DSS induced acute colitis was also reflected in higher local myeloperoxidase levels, higher inflammation scores of the colon, and higher systemic levels of interleukin 6 and serum amyloid P component. Local inflammatory parameters were also significantly different in heterozygous transgenic mice compared with wild-type mice, indicating a local dosage effect. In homozygous transgenic mice, significantly higher amounts of bacteria were found in organs but IgA levels were only slightly lower than those of control mice. CONCLUSION: Sufficiently high serum levels of alpha(1)-AGP result in a more aggressive development of acute colitis.

Acute Disease↗
PubMed2001

Oncostatin M regulates the synthesis and turnover of gp130, leukemia inhibitory factor receptor alpha, and oncostatin M receptor beta by distinct mechanisms.

The cytokine receptor subunits gp130, leukemia inhibitory factor receptor alpha (LIFRalpha), and oncostatin M receptor beta (OSMRbeta) transduce OSM signals that regulate gene expression and cell proliferation. After ligand binding and activation of the Janus protein-tyrosine kinase/STAT and mitogen-activated protein kinase signal transduction pathways, negative feedback processes are recruited. These processes attenuate receptor action by suppression of cytokine signaling and by down-regulation of receptor protein expression. This study demonstrates that in human fibroblasts or epithelial cells, OSM first decreases the level of gp130, LIFRalpha, and OSMRbeta by ligand-induced receptor degradation and then increases the level of the receptors by enhanced synthesis. The transcriptional induction of gp130 gene by OSM involves STAT3. Various cell lines expressing receptor subunits to the different interleukin-6 class cytokines revealed that only LIFRalpha degradation is promoted by activated ERK and that degradation of gp130, OSMRbeta, and a fraction of LIFRalpha involves mechanisms that are separate from signal transduction. These mechanisms include ligand-mediated dimerization, internalization, and endosomal/lysosomal degradation. Proteosomal degradation appears to involve a fraction of receptor subunit proteins that are ubiquitinated independently of ligand binding.

3T3 Cells↗
PubMed2001

Concepts for improved regioselective placement of O-sulfo, N-sulfo, N-acetyl, and N-carboxymethyl groups in chitosan derivatives.

In the present paper a new strategy has been studied to introduce solely or in combination N-sulfo, O-sulfo, N-acetyl, and N-carboxymethyl groups into chitosan with highest possible regioselectivity and completeness and defined distribution along the polymer chain. The aim was to generate compounds having lowest toxicity for determining the pharmacological structure function relationships among different backbone structures and differently arranged functional groups compared to those of heparin and heparan sulfate. The water-soluble starting material, chitosan, with a degree of acetylation (DA) of 0.14 and a molecular weight of 29 kD, allows one to apply most of the known reactions of chitosan as well as some reactions of heparin chemistry successfully and with improved regioselectivity and completeness. On the other hand, a number of these reactions were not successful by application to water-soluble high-molecular-weight chitosan (DA 0.45 and 150 kD). The starting material showed statistical N-acetyl (N-Ac) distribution along the polymer chain according to the rules of Bernoulli, with highest abundance of the GlcNAc-GlcNAc diad along with a lower abundance of triads, tetrads, and pentads. The space between the N-Ac groups was filled up in homogeneous reactions by N-sulfo and/or N-carboxymethyl groups, which also resulted in a Bernoulli statistical distribution. The N-substitution reaction showed highest regioselectivity and completeness with up to three combined different functional groups. The regioselectivity of the 3-O-sulfo groups was improved by regioselective 6-desulfation of nearly completely sulfated 3,6-di-O-sulfochitosan. By means of desulfation reactions, all of the possible intermediate sulfated products are possible. 6-O-Sulfo groups can also be introduced with highest regioselectivity and completeness, and a number of partially 6-desulfated products are possible.

Acetates↗
PubMed2001

A novel serine-dependent proteolytic activity is responsible for truncated signal transducer and activator of transcription proteins in acute myeloid leukemia blasts.

Hematopoietic cytokine receptor signaling involves activation of signal transducer and activator of transcription (STAT) proteins that are thought to control cellular differentiation. Truncated STAT isoforms (beta forms, rather than the normal alpha forms) have been described and found to block the normal signaling function of the alpha isoforms. We recently demonstrated STATbeta isoforms in bone marrow samples from 21 of 27 (78%) acute myeloid leukemia (AML) patients. We sought to determine the mechanism by which the STATbeta forms were generated. Samples from eight newly diagnosed AML patients were studied; four expressed predominantly STATalpha, and four expressed predominantly STATbeta. The reverse transcription-PCR generated identical products in the two groups, suggesting that alternate mRNA splicing is not responsible for the genesis of STATbeta. Extracts from cells expressing predominantly STATbeta incubated with cell extracts from the MO7E cell line, which expresses predominantly STATa, caused a decrease of the alpha isoforms and an increase of the beta isoforms, suggesting the presence of proteolytic activity. This proteolytic activity was: (a) specific for STAT3 and STAT5, but not for STAT6; (b) serine dependent; (c) equally present in nuclear and cytoplasmic fractions of the leukemic blasts; and (d) different than the activity detected in a murine hematopoietic cell line. The cleaved beta isoforms retained their DNA-binding activity. Because expression of truncated STATs may be involved in blocking differentiation of AML blasts, elucidation of the regulation of the proteolytic activity may contribute to our understanding of leukemogenesis.

Acute Disease↗
PubMed2001

Nuclear magnetic resonance studies of solvent flow through chromatographic columns: effect of packing density on flow patterns.

NMR (nuclear magnetic resonance) techniques have been used to measure and characterise solvent flow through chromatographic columns. NMR imaging was used to track an injection of D2O. PGSE (pulsed gradient spin echo) NMR was used to measure the flow-rate dependence of axial and transverse apparent diffusion. A combination of these two techniques (dynamic NMR imaging) gave the spatial distribution of the local velocity and apparent diffusion through a cross-section of the column. Significant column wall effects were observed and these effects were found to be highly dependent upon the column packing density. The column performance was assessed in terms of the HETP (height equivalent to a theoretical plate) determined by the NMR techniques employed.

Chromatography, Liquid↗
PubMed2001

Truncated STAT proteins are prevalent at relapse of acute myeloid leukemia.

Signal transducer and activator of transcription (STAT) proteins are implicated in the control of cell survival, proliferation and differentiation in response to hematopoietic cytokines. C-terminally truncated STAT isoforms (STATbeta), as opposed to the full length form (STATalpha), have a competitive or even transdominant negative effect on gene induction mediated by the STAT pathway. We have previously demonstrated that while constitutively active STAT proteins were detected in ten of 36 (28%) for STAT3 and eight of 36 (22%) for STAT5 in pretreatment samples from newly diagnosed acute myeloid leukemia (AML) patients, a significantly larger fraction of samples [21 of 27 (78%)] expressed STATbeta proteins. To determine whether STATbeta expression was maintained or increased after relapse in AML, we compared STAT activity and isoform expression at diagnosis and at relapse in 17 patients. In this selected group, constitutively active STAT3 was detected in 13 of 17 (76%) AML samples at diagnosis but was detected in only four of these patients at relapse. Constitutively active STAT5 was detected in three of 17 (18%) AML samples at diagnosis; but only two at relapse. In contrast, STATbeta protein expression was observed in 12 of the 17 pretreatment samples (71%) and in 16 of 17 samples at relapse. Only one patient did not express STATbeta at relapse. Our results suggest that STATbeta isoform expression, rather than level of constitutive activity, may be involved in disease progression in AML.

Adult↗
PubMed2001

The role of regioselectively sulfated and acetylated polysaccharide coatings of biomaterials for reducing platelet and plasma protein adhesion.

A brief survey is given about the role of natural polysaccharides such as heparin (HE), heparan sulfate (HS), chondroitin sulfate (CS), and dermatan sulfate (DS) in reducing blood coagulation and their potential use as athrombogenic coatings in the development of tailor-made athrombogenic biomaterials. Furthermore, known literature and new results about platelet adhesion on regioselectively modified polysaccharides such as HE, chitosan with HE-like functional groups, and sulfated cellulose are presented in two different perfusion systems at different shear rates. Regioselectively modified polysaccharides were tested as coatings of two polymers. The strongest influence on platelet adhesion was observed when the three regioselectively modified polysaccharides contained 6-O-sulfo- groups. No or little influence was seen with 3-O-sulfo- groups. A variable effect on platelet adhesion was found in position 2. N-sulfo- groups in HE induced a medium platelet adhesion, and O-sulfo- groups of iduronic acid moiety in HE induced none. Cellulose containing 2-O-sulfo- groups induced little platelet adhesion, and 2-N- sulfo- groups in chitosan induced a variable platelet adhesion response, depending on the N-SO(3)/NAc ratio. Preliminary plasma protein adhesion measurements on immobilized HE derivatives with four different fluorescence-labeled plasma proteins showed a regioselective influence with serum albumin and fibrinogen. 6-O-desulfated HE gave the strongest reduction in protein adsorption followed by N-desulfation and 2-O-desulfation; the lowest reduction was observed with 3-O-desulfation. Tailor-made athrombogenic coatings of HE should not carry high amounts of 6-O-sulfo- groups or of N-sulfo- groups. Regioselectively modified cellulose and chitosan may become suitable for tailor-made athrombogenic biomaterials when regioselective reactions are further optimized.

Acetylation↗
PubMed2001

Haptoglobin and the Th1/Th2 balance: hints from in vitro and in vivo studies.

A variety of immunomodulatory effects have previously been attributed to haptoglobin (Hp). These are supposed to be partly mediated through binding of Hp to CD11b. In the present study, we assessed its effects on T-helper (Th) cytokine production following both in vitro and in vivo stimulation of T-cells. Hp exhibits a dose-dependent inhibitory effect on human T lymphocyte release of the Th2 cytokines (IL-4, IL-5, IL-10 and IL-13) in vitro, whereas it has no clear effect on Th1 cytokine (IL-2 and IFN-gamma) release. When administered an anti-CD3 monoclonal antibody, Hp knockout mice produced more IL-4 and less IFN-gamma than did their wild-type litter-mates. Our findings imply that Hp may be regarded as a regulator of the Th1/Th2 balance in both human and murine immune systems.

Animals↗
PubMed2001

Haptoglobin, inflammation, and tumorigenesis in the MIN mouse.

We have determined that the MIN mouse, which is predisposed to adenomas of the small and large intestine, exhibits chronic inflammation characterized by the induction of haptoglobin (HP), as well as other acute phase proteins. Inflammation is initiated at about 40-70 days of age, and is maintained throughout the life of the animal. Delayed onset of inflammation brought on by dietary means is associated with a reduction in tumor number and longer life-span. Knockout mice that lack haptoglobin exhibit an increase in tumor number, indicating that the acute phase reactant suppresses tumorigenesis, perhaps through inhibition of the inflammatory response. The MIN mouse is, therefore, a useful model for studying the roles of HP and inflammation in tumorigenesis in vivo.

Adenoma↗
PubMed2001

Haptoglobin, an inflammation-inducible plasma protein.

Sterile tissue injury or infection initiates a local inflammatory response that mobilizes a systemic acute phase reaction resulting in, among other things, the induction of genes encoding the acute phase plasma proteins (APPs). In all vertebrates, a common set of APPs is increased and exerts essential protective functions. Haptoglobin (HP), one of the major APPs, acts as a high-affinity hemoglobin-binding protein and antioxidant. Liver is the major site of HP synthesis; however, regulated, low level expression is also detected in other organs. Induction of the Hp gene is mediated by interleukin-6-type cytokines and is synergistically enhanced by glucocorticoids. Growth stimulation of hepatic cells in vivo or in vitro suppresses the Hp gene-inducing effects of inflammatory cytokines. Receptors for IL-6 cytokines mediate induction of the Hp gene by the transcription factors signal transducer and activator of transcription-3 (STAT3) and CAAT/enhancer binding protein beta (C/EBPbeta), but attenuate the stimulation through co-activated STAT5 and mitogen-activated protein kinases, ERK-1 and ERK-2. The specificity by which the related cytokines, IL-6, oncostatin M, and leukemia inhibitory factor, regulate Hp gene transcription is determined by the profile of the cytokine receptor subunits expressed on the target cells and the relative extents by which these receptors activate the intracellular signaling pathways. The current hypothesis is that HP exerts an anti-inflammatory activity and that by the degree with which HP attenuates the inflammatory process, including the production of IL-6 cytokines, it determines the level and duration of acute phase expression of the Hp gene.

Animals↗
PubMed2000

Stimulation of leukemia inhibitory factor receptor degradation by extracellular signal-regulated kinase.

Leukemia inhibitory factor (LIF) signals via the heterodimeric receptor complex comprising the LIF receptor alpha subunit (LIFRalpha) and the common signal transducing subunit for interleukin-6 cytokine receptors, gp130. This study demonstrates that in different cell types, the level of LIFRalpha decreases during treatment with LIF or the closely related cytokine oncostatin M (OSM). Moreover, insulin and epidermal growth factor induce a similar LIFRalpha down-regulation. The regulated loss of LIFRalpha is specific since neither gp130 nor OSM receptor beta shows a comparable change in turnover. LIFRalpha down-regulation correlates with reduced cell responsiveness to LIF. Using protein kinase inhibitors and point mutations in LIFRalpha, we demonstrate that LIFRalpha down-regulation depends on activation of extracellular signal-regulated kinase 1/2 and phosphorylation of the cytoplasmic domain of LIFRalpha at serine 185. This modification appears to promote the endosomal/lysosomal pathway of the LIFRalpha. These results suggest that extracellular signal-regulated kinase-activating factors like OSM and growth factors have the potential to lower specifically LIF responsiveness in vivo by regulating LIFRalpha half-life.

3T3 Cells↗