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G Hübner

Publications and source records attributed to G Hübner.

At least 55 records · Page 3Linked to original sources
PubMed1997

Activin A: a novel player and inflammatory marker in inflammatory bowel disease?

Recently, we demonstrated a strong induction of activin expression after cutaneous injury. We speculated, therefore, that activin may be overexpressed during inflammatory processes in other tissues characterized by mesenchymal/epithelial structure. Herein, we show a strikingly increased expression of the activin beta A-subunit in surgical specimens from the gut of patients suffering from ulcerative colitis and Crohn's disease, whereas no activin beta A mRNA could be detected in the normal human digestive tract. The levels of activin beta A expression showed an outstanding correlation with the degree of inflammation as assessed by histologic analysis of adjacent tissue and expression analysis of the proinflammatory cytokine interleukin-1 beta. In situ hybridization studies revealed the highest levels of activin mRNA in the mucosa and submucosa of highly inflamed areas, particularly where the intestinal epithelium was damaged, but not in control tissue. In contrast, activin beta B mRNA levels in most specimens from inflamed areas were only slightly higher compared to control tissue. The strong overexpression of activin beta A in inflammatory bowel disease suggests a novel and important role of this growth and differentiation factor during inflammatory processes of the gut.

Activins↗
PubMed1996

Serum growth factors and proinflammatory cytokines are potent inducers of activin expression in cultured fibroblasts and keratinocytes.

Recently we demonstrated a large induction of activin expression in fibroblasts and keratinocytes after cutaneous injury in mice. To identify possible mediators of activin induction during skin repair, we have now analyzed the regulation of this factor in cultured keratinocytes and fibroblasts. Here we show that activin A mRNA and protein levels are low in quiescent keratinocytes and fibroblasts but expression is strongly induced upon serum treatment. The stimulatory effect of serum on activin expression is likely to be a combinatorial effect of different growth factors, since platelet-poor plasma serum and several purified serum growth factors also stimulated activin expression, although to a lesser extent than complete serum. Furthermore, we found increased expression of activin in keratinocytes and fibroblasts after addition of the proinflammatory cytokines interleukin 1beta and tumor necrosis factor alpha. Taken together, our data suggest that serum growth factors which are released upon hemorrhage as well as proinflammatory cytokines derived from neutrophils and macrophages might be responsible for induction of activin expression after injury.

3T3 Cells↗
PubMed1996

Strong induction of activin expression after hippocampal lesion.

We studied the temporal and spatial mRNA expression pattern of activin/inhibin beta A, beta B and alpha subunits after unilateral kainic acid lesions of the hippocampal CA3 region. We found a strikingly increased expression of beta A mRNA in the ipsilateral hippocampus 6-24 h after injury. By contrast, the beta B and alpha mRNAs were expressed at equally low levels in normal and injured hippocampi, suggesting that the beta A transcripts give rise to activin A, but not to activin AB or inhibin. In situ hybridization demonstrated the presence of beta A mRNA in neurones near the site of lesion. Expression of all known types of activin receptors could be demonstrated in normal and injured hippocampi by RT-PCR. These findings suggest a role of activin in brain injury.

Activins↗
PubMed1996

[Intensive post-remission therapy in acute myeloid leukemia. Results of a prospective comparative study by the South Germany Hemoblastosis Group].

BACKGROUND: To study intensive postremission therapy in adult patients with acute myeloid leukemia myeloablative therapy followed by allogeneic or unpurged autologous bone marrow transplantation (BMT) was compared with high-dose cytosine-arabinoside/daunorubicin (HDAC) consolidation. PATIENTS AND METHODS: 148 de novo AML patients of maximum 50 years (median 36 years, range 16 to 50) were enrolled in the trial. Following induction and early consolidation chemotherapy consisting of daunorubicin, cytosine-arabinoside and VP-16 (DAV), patients with an HLA-identical sibling underwent allogeneic BMT. The other patients received (by randomization or patient's decision) either HDAC or high-dose busulfan plus cyclophosphamide followed by autologous BMT. RESULTS: Hundred and five 105 (70.9%) patients achieved a complete remission. The event-free survival rates after intensive postremission therapy after 72 months were: after BMT (24 patients) 62% (95% confidence interval +/- 19%), after HDAC (44 patients) 36 +/- 16% and after autologous BMT (12 patients) 18 +/- 22%. Thus allogeneic BMT was superior to autologous BMT (p = 0.04), as was HDAC compared to autologous BMT, although not significantly so (p = 0.15). Patients receiving 2 cycles of HDAC had a better 6-year event-free survival rate (47%) and a lower relapse rate (50%) than patients who received only 1 course (29% and 70% respectively). CONCLUSIONS: High-dose busulfan/cyclophosphamide followed by unpurged autologous BMT early after achieving CR had no advantage over high-dose ara-c/daunorubicin. Two cycles of HDAC yielded better results than 1 cycle. The highest event-free survival rate was reached with myeloablative therapy followed by allogeneic BMT.

Adolescent↗
PubMed1996

[10 years transplantation of bone marrow and hematopoietic stem cells in adults at the Hannover Medical School].

PATIENTS AND METHODS: From January 1986 until August 1995 230 adult patients received an allogeneic or autologous transplantation of bone marrow or hematopoietic blood stem cells. The conditioning and myeloablative treatment regimens were chosen according to the underlying disease and type of transplant. RESULTS: The observation period comprises 1 to 115 months after transplantation. After allogeneic transplantation from HLA-identical family donors, the probabilities of disease-free survival were for acute myeloid leukemia in first complete remission (CR) (n = 35) 77%, for acute lymphoid leukemia in 1st CR (n = 7) 72% and in 2nd CR (n = 10) 40%, in first chronic phase of chronic myeloid leukemia (n = 34) 50% and in severe aplastic anemia (n = 7) 100%. Following myeloablative therapy and autologous transplantation the probabilities of disease-free survival were 47% in relapsed Hodgkin's disease (n = 22) and 42% for relapsed high-grade non-Hodgkin's lymphoma (n = 12). Eight of 10 patients with acute myeloid and 7 of 8 with acute lymphoid leukemia suffered a leukemic relapse after autologous bone marrow transplantation. Three of 8 patients with relapsed testicular cancer survived relapse-free. Treatment failures were due to more advanced acute graft versus host disease after allogeneic transplantation and caused by relapse after autologous transplantation. Current protocols evaluate the allogeneic transplantation of enriched CD34+ blood stem cells. In chronic myeloid leukemia the autologous transplantation of blood stem cells after myeloablative therapy is being studied.

Adolescent↗
PubMed1996

Strong induction of activin expression after injury suggests an important role of activin in wound repair.

Activins are members of the transforming growth factor beta (TGF beta) superfamily, which comprises a growing group of dimeric proteins. TGF beta and several other members of this superfamily are known to play an important role in wound healing. However, expression of activin during wound healing has not been demonstrated so far. In this study we have analyzed the expression pattern of activin and activin receptors in normal and wounded skin. We found a large induction of activin A and a minor induction of activin B mRNA expression 1 day after skin injury and high expression levels of activin A and B were found within the first 7 days after wounding. At 13 days after injury, expression of activin A mRNA had returned to the basal level, whereas high levels of activin B persisted. In situ hybridization studies revealed expression of activin A in the granulation tissue below the wound and activin B in the hyperproliferative epithelium at the wound edge and in the migrating epithelial tongue. All known types of activin receptors as well as the activin binding protein follistatin were expressed in normal and wounded skin. However, no significant induction of receptor gene expression was seen during the repair process. The distribution of activins and activin receptors in the wound suggests multiple autocrine and paracrine activities of the ligands during wound healing. Our data provide evidence for a novel function of activin and indicate that--besides TGF beta s themselves--other members of this superfamily might also play an important role in tissue repair.

Activin Receptors↗
PubMed1996

Differential regulation of pro-inflammatory cytokines during wound healing in normal and glucocorticoid-treated mice.

It has long been speculated that pro-inflammatory cytokines play an important role in wound repair. However, little is known about the temporal and spatial expression pattern of these cytokines during normal and impaired wound healing. In this study we show a strong and early induction of interleukins 1 alpha and beta (IL-alpha and beta) and of tumour necrosis factor alpha (TNF-alpha) expression after cutaneous injury. Highest levels of these cytokines were seen as early as 12-24 h after wounding. After completion of the proliferative phase of wound healing, mRNA levels of these cytokines returned to the basal level. During the early phase of wound repair, proinflammatory cytokines were predominantly expressed in polymorphonuclear leukocytes, suggesting a novel function of these cells in the initiation of wound healing. At later stages of the repair process, expression of IL-1 alpha, IL-1 beta and TNF-alpha was also seen in macrophages. Furthermore, TNF-alpha was detected in the hyperproliferative epithelium at the wound edge and IL-1 alpha was found in keratinocytes of the hair follicles. Induction of these cytokines after injury was significantly reduced during wound repair in healing-impaired glucocorticoid-treated mice. This finding demonstrates that wound healing defects are associated with impaired cytokine expression and suggests that the early induction of these genes is important for normal repair.

Animals↗
PubMed1996

Purification and characterisation of the pyruvate decarboxylase from a haploid strain of Saccharomyces cerevisiae.

A novel purification procedure was developed for pyruvate decarboxylase (PDC, E.C. 1.1.1.4) from the haploid yeast strain YSH 4.127-1A expressing only one (PDC1) of the three structural genes for PDC. The purified enzyme is homotetrameric with a molecular mass of about 240,000 whereas PDC from brewer's yeast is a dimer of dimers composed of subunits of different size (alpha 2 beta 2) with the same molecular mass as the tetramer. Despite these structural variations there are no significant differences in the kinetic behaviour of the two enzyme species. PDC purified from the haploid yeast mutants shows a sigmoid dependence of the reaction rate from the substrate concentration due to the substrate activation. In the presence of the substrate surrogate pyruvamide the shape of the v/S plot is transformed into a hyperbolic one. As expected, polyclonal antibodies react with both the enzyme from haploid yeast strain mutants and that from brewer's yeast.

Ammonium Sulfate↗
PubMed1995

Influence of phosphoenolpyruvate and magnesium ions on the quaternary structure of enzyme I of the phosphotransferase system from gram-positive bacteria.

Solution X-ray scattering patterns of enzyme I of the phosphotransferase system from Staphylococcus carnosus indicate an increase in radius of gyration and molecular mass in the presence of Mg2+ or both Mg2+ and phosphoenolpyruvate, indicating a partial dimerization of enzyme I. Mg2+ ions are essential for both the dimerization and the activation, whereas the substrate phosphoenolpyruvate shifts the monomer--dimer equilibrium to the enzymatically active dimer by decreasing the dissociation rate of the phosphorylated dimer.

Enzyme Activation↗
PubMed1995

Regulation of vascular endothelial growth factor expression in cultured keratinocytes. Implications for normal and impaired wound healing.

Recent in situ hybridization studies had demonstrated a strong increase in vascular endothelial growth factor (VEGF) mRNA expression in the hyperproliferative epithelium during wound healing. To determine potential mediators of VEGF induction during this process, we analyzed the regulation of VEGF expression in cultured human keratinocytes. We found a large induction of VEGF expression upon treatment of quiescent cells with serum, epidermal growth factor, transforming growth factor-beta 1, keratinocyte growth factor, or the proinflammatory cytokine tumor necrosis factor alpha, respectively. Since all these factors are present at the wound site during the early phase of wound healing, they might also be responsible for VEGF induction after cutaneous injury. To determine the importance of increased VEGF production for wound repair, we compared the time course of VEGF mRNA expression during wound healing of healthy control mice with the kinetics of VEGF expression during skin repair of genetically diabetic db/db mice which are characterized by impaired wound healing. In normal mice we found elevated VEGF mRNA levels during the period when granulation tissue formation occurs. In contrast, VEGF mRNA levels even declined during this period in db/db mice, suggesting that a defect in VEGF regulation might be associated with wound healing disorders.

Animals↗
PubMed1995

Purification and characterisation of pyruvate decarboxylase from pea seeds (Pisum sativum cv. Miko).

Pyruvate decarboxylase (PDC) was purified from pea seeds. The catalytically active holoenzyme is an oligomer of two types of subunits with molecular masses of about 65 kDa and 68 kDa, respectively. The active enzyme is a mixture of tetramers, octamers and even higher oligomers. These differences in the quaternary structure compared with PDC from yeast (tetramer) do not result in a different kinetic behaviour. The activity of pea PDC as well as that of yeast PDC is regulated by its substrate pyruvate resulting in a sigmoid shape of the v/S-plot. At the optimum pH of 6.0 a S0.5-value of 1 mM pyruvate is found that increases with rising pH and increasing concentrations of phosphate. The substrate analogue activator pyruvamide activates the enzyme resulting in a hyperbolic v/S-plot. The stability of PDC from pea seeds in solution is about one order of magnitude higher than that of yeast PDC. Despite the described similarities of the two enzymes no significant cross reactivity of the anti-pea PDC antibody with the enzyme from yeast occurs.

Blotting, Western↗
PubMed1995

DNA fingerprint analysis in acute leukemias.

Restriction fragment length polymorphism (RFLP) analysis by Southern blotting or direct in-gel hybridization is a routine procedure in any genetic laboratory. Minisatellites and simple repeat probes for RFLP analysis have proved to be highly informative genetic markers, depending on their degree of homology and index of heterozygosity. Several of these probes have considerable individualization potential, thus yielding 'fingerprint' pattern. In the setting of acute leukemia DNA fingerprint (DNA-F) analysis is able to provide considerable information concerning the genetic instability of the leukemic clone. DNA-F is capable of detecting randomly occurring genetic alterations of unknown localization and to identify new hotspots of malignant transformation. As DNA-F analysis is not likely to be hampered by the effects of chemotherapy or DNA methylation, altered fingerprints may be regarded as characteristic of the leukemic clone. With the introduction of polymerase chain reaction (PCR) and increasing sensitivity, DNA-F analysis is likely to be of significant importance in monitoring minimal residual disease in human leukemia.

DNA Fingerprinting↗
PubMed1994

[Doppler ultrasound evaluation of blood flow direction in distal occlusion of arteries of the lower leg].

It is necessary to observe the direction of the blood flow for measurement of the ankle pressure by the Dopplermethod. Obliteration of the ankle pressure by the Dopplermethod. Obliteration of the anterior tibial artery can be compensated by collaterals from the posterior tibial artery. Through this the blood flow is reversed in the dorsalis pedis artery. If this possibility is disregarded, the pressure of the anterior tibial artery will yield false data. The situation of the blood flow can be clarified by a compression test of the posterior tibial artery. This also applies to obliterations of the other arteries of the ankle.

Arterial Occlusive Diseases↗
PubMed1994

Induction of keratinocyte growth factor expression is reduced and delayed during wound healing in the genetically diabetic mouse.

We have recently demonstrated induction of expression of several members of the fibroblast growth factor family during wound healing, particularly for keratinocyte growth factor, which was more than 150-fold induced within 24 h after injury. To assess whether wound-healing disorders are associated with a defect in fibroblast growth factor regulation, we have now investigated the expression of these mitogens as well as their receptors in normal and wounded skin of genetically diabetic db/db mice, which are characterized by their impaired wound healing. We demonstrate that induction of keratinocyte growth factor expression in these mice is significantly reduced and delayed compared to normal mice. Induction of acidic fibroblast growth factor (FGF) and basic FGF expression was earlier in diabetic mice than in normal mice, but by 3 d after injury expression of these mitogens had already returned to the basal levels. In contrast, elevated levels of acidic FGF and basic FGF transcripts were detected within the first 5 d in wounds from normal mice. Thus, FGFs seem to be expressed in a limited fashion in the wound tissue of db/db mice during the period when re-epithelialization and granulation tissue formation normally occur. These findings provide an explanation for the beneficial effect of exogenous FGF in the treatment of impaired wound healing in these animals and suggest that induction of KGF early in repair may be critical for the rapid re-epithelialization in normal wound healing.

Animals↗
PubMed1994

Nonlinear dynamic processes in open single enzyme systems.

Chemical oscillations are predicted theoretically in single enzyme systems open to substrate containing a regulatory enzyme, which shows a slow substrate activation. The time-evolution of the system is well described by two ordinary differential equations. The conditions for oscillations or overshoot phenomena of the substrate concentration were analysed by numerical simulation. The existence of damped oscillations or overshoot phenomena in a regulatory enzyme reaction, open to substrate, has been proved experimentally in the pyruvate decarboxylase reaction and in the pyruvate dehydrogenase reaction. In both cases the concentration of the substrate pyruvate shows a strongly damped oscillation in a concentration range below the Km-value.

Binding Sites↗
PubMed1994

Large induction of keratinocyte growth factor expression by serum growth factors and pro-inflammatory cytokines in cultured fibroblasts.

We have recently demonstrated a large induction of keratinocyte growth factor expression in dermal fibroblasts during wound healing. To identify possible mediators of KGF induction, we have now analysed the regulation of KGF expression in vitro in cultured murine and human fibroblasts. Here we demonstrate that KGF mRNA and protein expression is low in quiescent fibroblasts but is strongly induced upon serum stimulation. This induction can be mediated by at least two different intracellular pathways involving protein kinase C or cAMP-dependent kinases. Our finding that induction of KGF expression by serum is independent of de novo protein synthesis demonstrates, that KGF is the product of a primary response gene. The stimulatory effect of serum on KGF expression is likely to be a combinatorial effect of different mitogens, since several purified serum growth factors also stimulated KGF expression but to a lesser extent compared to serum. Furthermore, we also found a strong KGF induction by interleukin-1 beta, tumor necrosis factor-alpha and interleukin-6, cytokines which are released by polymorphonuclear leukocytes and activated macrophages during wound healing. These data suggest that serum which is released upon hemorrhage as well as pro-inflammatory cytokines might be responsible for the KGF induction in vivo during skin repair.

3T3 Cells↗
PubMed1993

The influence of the effectors of yeast pyruvate decarboxylase (PDC) on the conformation of the dimers and tetramers and their pH-dependent equilibrium.

The influence of effectors of yeast pyruvate decarboxylase, phosphate, pyruvamide, thiamin diphosphate and Mg++, on the pH-dependent equilibrium between dimers and tetramers was studied by synchrotron radiation X-ray solution scattering. Thiamin diphosphate and phosphate shift the equilibrium to higher pH values without altering the structure of the oligomers. Pyruvamide, a substrate analogue activator, induces a significant change in the structure of the tetramer. By eliminating radiation damage by addition of dithioerythrol to the buffers, the scattering curves could be measured accurately over a large angular range. They were expanded in terms of spherical harmonics to obtain the shapes of the dimers and tetramers with higher resolution than was hitherto possible. This also allowed us to position the dimers, which are centrosymmetric at low resolution, in the tetramers which have 222 symmetry. The results indicate that addition of pyruvamide results in a less compact tetramer owing to structural changes in the dimers and to their displacements.

Biophysical Phenomena↗