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J Pfeilschifter

Publications and source records attributed to J Pfeilschifter.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Evaluation of osteoporosis].

Physical examination, bone densitometry and x-ray are the mainstay in the evaluation of osteoporosis. A limited number of simple blood tests are sufficient to discriminate most secondary forms of osteoporosis and to exclude osteomalacia. Bone-specific biochemical markers play an increasing role in monitoring osteoporosis therapy. They may also play a role in treatment decision in the coming years. Bone biopsies are helpful if findings are unclear or inconsistent. The present review gives a summary of the opportunities and limitations of the above diagnostic procedures.

Absorptiometry, Photon↗
PubMed2002

[Disordered hormone regulation in gynecomastia].

Gynecomastia develops when there is an increase in the ratio of estrogen to androgens. Whereas mild forms of gynecomastia are frequently encountered in the male population, any breast enlargement that is prominent, painful, progressive or of recent onset always requires a careful evaluation, as it may be an important clue to disease elsewhere. Underlying causes are plenty and include drugs, congenital and acquired disorders of androgen and estrogen production, various tumors, renal failure, cirrhosis of the liver, and thyrotoxicosis. Evaluation includes a careful patient's history, physical examination of sexual characteristics and the breast tissue, and measurements of serum LH, FSH, testosterone, estradiol, hCG-beta, TSH and tests of liver and kidney function.

Androgens↗
PubMed2001

Proteolytic cleavage of inducible nitric oxide synthase (iNOS) by calpain I.

Proteolytic degradation of inducible nitric oxide synthase (iNOS or NOS2; EC 1.14.13.39) is one of the key steps by which the synthetic glucocorticoid dexamethasone controls the amount of iNOS protein and thus the production of nitric oxide (NO) in interferon-gamma-stimulated RAW 264.7 cells. In the present study we examined the role of the calmodulin (CaM)-binding site present within iNOS protein for the proteolytic degradation by the calcium-dependent neutral cysteine protease calpain I (EC 3.4.22.17). Using pulse chase experiments as well as cell-free degradation assays we show that the iNOS monomer is a direct substrate for cleavage by calpain I. Two structural determinants are involved in proteolytic cleavage, the canonical CaM-binding domain present at amino acids 501-532 and a conformational determinant located within iNOS. The access of the CaM-binding region appears to be critical for substrate cleavage as incubation of in vitro synthesized iNOS with purified CaM inhibits iNOS degradation by calpain I. Moreover, cytosolic CaM levels are decreased upon treatment of RAW 264.7 cells with dexamethasone as assessed by immunoprecipitation. The data shown herein provide novel insights into the underlying mechanisms involved in the anti-inflammatory actions of glucocorticoids.

Animals↗
PubMed2001

Expression and release of IL-18 binding protein in response to IFN-gamma.

IL-18 and IL-18 binding protein (IL-18BP) are two newly described opponents in the cytokine network. Local concentrations of these two players may determine biological functions of IL-18 in the context of inflammation, infection, and cancer. As IL-18 appears to be involved in the pathogenesis of Crohn's disease and may modulate tumor growth, we investigated the IL-18/IL-18BPa system in the human colon carcinoma/epithelial cell line DLD-1. In this study, we report that IFN-gamma induces expression and release of IL-18BPa from DLD-1 cells. mRNA induction and secretion of IL-18BPa immunoreactivity were associated with an activity that significantly impaired release of IFN-gamma by IL-12/IL-18-stimulated PBMC. Inducibility of IL-18BPa by IFN-gamma was also observed in LoVo, Caco-2, and HCT116 human colon carcinoma cell lines and in the human keratinocyte cell line HaCaT. Induction of IL-18BPa in colon carcinoma/epithelial cell lines was suppressed by coincubation with sodium butyrate. IFN-gamma-mediated IL-18BPa and its suppression by sodium butyrate were confirmed in organ cultures of intestinal colonic biopsy specimens. In contrast, sodium butyrate did not modulate expression of IL-18. The present data suggest that IFN-gamma may limit biological functions of IL-18 at sites of colonic immune activation by inducing IL-18BPa production. Down-regulation of IL-18BPa by sodium butyrate suggests that reinforcement of local IL-18 activity may contribute to actions of this short-chain fatty acid in the colonic microenvironment.

Butyrates↗
PubMed2001

Downregulation of integrin-linked kinase mRNA expression by nitric oxide in rat glomerular mesangial cells.

Inflammatory glomerular diseases are accompanied by changes in the expression patterns of growth factors, mediators and matrix-associated proteins in mesangial cells and by the production of nitric oxide via the cytokine-inducible form of the nitric oxide synthase. Nitric oxide has been shown to act potently on gene transcription. To identify genes that are differentially expressed by endogenously produced nitric oxide, we forced rat mesangial cells to produce high amounts of nitric oxide by exposure to inflammatory cytokines and compared the mRNA expression patterns of cytokine-stimulated mesangial cells with cells that were additionally treated with the nitric oxide synthase inhibitor L-NMMA to block endogenous NO synthesis. We used a modification of a low stringency RT-PCR approach designated as RNA arbitrarily-primed polymerase chain reaction (RAP-PCR). In this way, we identified among others the integrin-linked kinase (ILK) as an NO-regulated gene. The NO-mediated changes in the mRNA and protein expression patterns of ILK were compared to that of "secreted protein acidic and rich in cystein" (SPARC), a gene that was identified as NO-regulated in the same set of experiments (Walpen et al., J. Am. Soc. Nephrol., 11, 468-476). ILK and SPARC mRNA levels by were downregulated by cytokines via endogenously produced nitric oxide in a comparable manner as verified by Northern blot analysis. In contrast, cytokine- induced NO production or administration of exogenous NO-donors strongly reduced SPARC protein levels without altering ILK protein content in mesangial cells over a period up to 72 hours. Blocking de novo protein synthesis showed a short halflife of SPARC (< 2 hours) whereas ILK-protein was stable over a period of 7 hours, indicating that NO-mediated reduction of ILK mRNA levels does not influence protein content of ILK in mesangial cells under the time limitations given under cell culture conditions. However, a role for cytokines/NO in ILK-long-term regulation in chronic inflammatory diseases that may influence phenotypic responses such as apoptosis or cell proliferation remains to be elucidated.

Animals↗
PubMed2001

Nitric oxide and mechanisms of redox signalling: matrix and matrix-metabolizing enzymes as prime nitric oxide targets.

One of the greatest biomedical breakthroughs of the twentieth century was the discovery of endothelium-derived relaxing factor and its identification as nitric oxide (NO). NO has received special attention ever since: besides its potent vasodilatory and vasoprotective effects, NO was identified as a key player in innate immunity and was found to act as an unconventional type of neurotransmitter. This article focuses on mechanisms of NO signalling that form the basis of functional cell responses to accommodate changes in the cellular microenvironment. Redox-based regulation of signal transduction and, on a more long-term scale, changes in gene expression will be exemplified by NO-modulation of matrix components and matrix-metabolizing enzymes. It seems to be a safe bet that ongoing analyses of NO signalling and gene expression will provide a wealth of promising therapeutic targets in human diseases.

Animals↗
PubMed2001

Interleukin-1beta induces chronic activation and de novo synthesis of neutral ceramidase in renal mesangial cells.

The lipid signaling molecule ceramide is formed by the action of acid and neutral sphingomyelinases and degraded by acid and neutral ceramidases. Short-term stimulation of mesangial cells with the pro-inflammatory cytokine interleukin-1beta (IL-1beta) leads to a rapid and transient increase in neutral sphingomyelinase activity (Kaszkin, M., Huwiler, A., Scholz, K., van den Bosch, H., and Pfeilschifter, J. (1998) FEBS Lett. 440, 163-166). In this study, we report on a second delayed peak of activation occurring after hours of IL-1beta treatment. This second phase of activation was first detectable after 2 h of treatment and steadily increased over the next 2 h, reaching maximal values after 4 h. In parallel, a pronounced increase in neutral ceramidase activity was observed, accounting for a constant or even decreased level of ceramide after long-term IL-1beta treatment, despite continuous sphingomyelinase activation. The increase in neutral ceramidase activity was due to expressional up-regulation, as detected by an increase in mRNA levels and enhanced de novo protein synthesis. The increase in neutral ceramidase protein levels and activity could be blocked dose- dependently by the p38 MAPK inhibitor SB 202190, whereas the classical MAPK pathway inhibitor U0126 and the protein kinase C inhibitor Ro 318220 were ineffective. Moreover, cotreatment of cells for 24 h with IL-1beta and SB 202190 led to an increase in ceramide formation. Interestingly, IL-1beta-stimulated neutral ceramidase activation was not reduced in mesangial cells isolated from mice deficient in MAPK-activated protein kinase-2, which is a downstream substrate of p38 MAPK, thus suggesting that the p38 MAPK-mediated induction of neutral ceramidase occurs independently of the MAPK-activated protein kinase-2 pathway. In summary, our results suggest a biphasic regulation of sphingomyelin hydrolysis in cytokine-treated mesangial cells with delayed de novo synthesis of neutral ceramidase counteracting sphingomyelinase activity and apoptosis. Neutral ceramidase may thus represent a novel cytoprotective enzyme for mesangial cells exposed to inflammatory stress conditions.

Amidohydrolases↗
PubMed2001

Superoxide potently induces ceramide formation in glomerular endothelial cells.

Recent evidence suggests that the sphingolipid-derived second messenger ceramide and oxidative stress are intimately involved in apoptosis induction. Here we report that exposure of microcapillary glomerular endothelial cells to superoxide-generating substances, including hypoxanthine/xanthine oxidase and the redox cyclers DMNQ and menadione results in a dose-dependent and delayed increase in the lipid signaling molecule ceramide. Long-term incubation of endothelial cells for 2-30 h with either DMNQ or hypoxanthine/xanthine oxidase leads to a continuous increase in ceramide levels. In contrast, short-term stimulation for 1 min up to 1 h had no effect on ceramide formation. The DMNQ-induced delayed ceramide formation is dose-dependently inhibited by reduced glutathione, whereas oxidized glutathione was without effect. Furthermore, N-acetylcysteine completely blocks DMNQ-induced ceramide formation. All superoxide-generating substances were found to dose-dependently trigger endothelial cell apoptosis. In addition, glutathione and N-acetylcysteine also prevented superoxide-induced apoptosis and implied that ceramide represents an important mediator of superoxide-triggered cell responses like apoptosis.

Acetylcysteine↗
PubMed2001

Nitric oxide induces MIP-2 transcription in rat renal mesangial cells and in a rat model of glomerulonephritis.

Nitric oxide is a crucial mediator of several forms of glomerulonephritis. We examined the effects of NO on the mRNA expression pattern in glomerular mesangial cells by using a low-stringency reverse transcriptase-polymerase chain reaction method and detected a cDNA fragment that was induced by interleukin 1b (IL-1b) and further up-regulated by the NO donor diethylenetriamine-nitric oxide (DETA-NO). Each respective cDNA fragment was found to match with the cDNAs of rat macrophage inflammatory protein 2 (MIP-2) and GRO/cytokine-induced neutrophil chemoattractant 2b (CINC-2b). Further characterization of MIP-2 regulation by Northern blot analysis confirmed an NO- and IL-1b-dependent increase in MIP-2 mRNA levels. Moreover, inhibition of IL-1b-induced endogenous NO formation by the NO-synthase (NOS) inhibitor L-NMMA markedly attenuated MIP-2 protein expression. We cloned 770 bp of the 5'-flanking region of rat MIP-2 and fused this fragment to a luciferase reporter gene. Transfection of the construct into mesangial cells resulted in a 3.5-fold increase in luciferase activity in cells treated with DETA-NO when compared to controls, suggesting a transcriptional mechanism for NO-induced MIP-2 expression. Deletion and mutational analysis identified critical nuclear factor (NF)-kB and NF-IL-6 binding sites required for NO regulation of MIP-2. In vivo, inhibition of NO synthesis in the Thy-1.1 model of mesangioproliferative glomerulonephritis by the specific inducible-NOS inhibitor L-NIL resulted in a marked reduction of MIP-2 mRNA expression. Furthermore, infiltration of neutrophils into the glomerulus was dramatically attenuated in L-NIL-treated rats.

Amidines↗
PubMed2001

Systemically and topically supplemented leptin fails to reconstitute a normal angiogenic response during skin repair in diabetic ob/ob mice.

AIMS/HYPOTHESIS: In diabetic patients impaired wound healing conditions are a therapeutic problem of clinical importance. Recently, we showed that supplemented leptin induced an acceleration of impaired wound closure in diabetic ob/ob mice by reversion of the delayed re-epithelialization process. Additionally, angiogenesis is central to a normal repair. As leptin has been reported to represent an angiogenic factor, we hypothesized that leptin-mediated angiogenic processes at the wound site might participate in leptin-mediated improvement of disturbed repair in ob/ob mice. METHODS: Using a model of excisional wounding, C57BL/6J-ob/ob mice were treated systemically and topically with recombinant murine leptin during the phase of repair. Changes in blood glucose concentrations and body weight were monitored. We measured expression of the vascular endothelial growth factor (VEGF) and the endothelial cell marker protein CD31 as a read-out for angiogenic processes at the wound site. RESULTS: Expression of VEGF protein upon injury was reduced (30 to 40%) in ob/ob mice compared with wild-type C57BL/6 animals. Systemic and topical administration of leptin reconstituted normal wound VEGF expressions but failed to reverse the strongly reduced angiogenic response in ob/ob mice. Immunohistochemistry confirmed that the epithelium and blood vessels located in the granulation tissue expressed the functional leptin receptor obRb isoform during skin repair. CONCLUSION/INTERPRETATION: These data suggest that leptin reconstituted epithelial expression of VEGF during skin repair in ob/ob mice but failed to improve wound angiogenesis in the granulation tissue. Thus, the accelerated wound closure observed in leptin-supplemented ob/ob mice is not coupled to an improved wound angiogenesis.

Administration, Topical↗
PubMed2001

[Hormone replacement and selective estrogen receptor modulators (SERMS) in the prevention and treatment of postmenopausal osteoporosis].

For many years, hormone replacement therapy (HRT) has been regarded as one of the most reliable means of prophylaxis and treatment for postmenopausal osteoporosis. As HRT ameliorates menopausal symptoms, it is widely prescribed among early postmenopausal women. A variety of different modes of replacement that suit each individual requirement are available in terms of schedule (cyclic or combined application of gestagens) and route of application (oral or transdermal). HRT effectively prevents spinal bone loss and delays bone loss at the hip up to a very old age. With continued use after menopause, HRT might theoretically halve the incidence of vertebral and hip fractures. However, long-term use or use of HRT in old age is rarely practiced, and the actual benefit of a transient use for future fracture prevention remains unclear. Raloxifene is the first member of the novel class of selective estrogen receptor modulators (SERMs) that has been approved for the prophylaxis and treatment of postmenopausal osteoporosis. It combines the positive effects of estrogen on the skeleton with estrogen-antagonistic effects on sex tissues. Thus, raloxifene maintains bone mass and decreases the incidence of vertebral fractures in osteoporotic women, but avoids many of the side effects that are responsible for the poor long-term compliance to HRT such as resumption or continuation of regular menses, breast tenderness, or breast cancer. It even markedly reduces the risk of breast cancer. Both estrogen and raloxifene are characterized by a large number of extraskeletal effects that have to be taken into account when counseling postmenopausal women on the use of these agents for the prevention or treatment of osteoporosis.

Administration, Oral↗
PubMed2001

Association of transforming growth factor-beta1 (TGFbeta1) T29 --> C gene polymorphism with bone mineral density (BMD), changes in BMD, and serum concentrations of TGF-beta1 in a population-based sample of postmenopausal german women.

TGF-beta1 is thought to play an important role in bone turnover. Thus, the gene encoding TGF-beta1 is a prime candidate for the genetic regulation of bone density. Recent studies have suggested that a T29 --> C polymorphism in the signal sequence region of the TGF-beta1 gene may be related to bone mineral density (BMD) and bone loss in postmenopausal Japanese women. In the present study, we examined the relationship between this polymorphism and BMD in a population-based sample of 102 estrogen-deficient postmenopausal women from the Heidelberg cohort of the European Vertebral Osteoporosis Study (EVOS). Average BMD in women with the TT genotype was approximately 10% higher at both the lumbar spine and the femoral neck compared with women with the CC genotype (spine: 980 vs. 887 mg/cm2, P = 0.05; femoral neck: 755 vs. 674 mg/cm2; P = 0.02). Women with the TT genotype also experienced less overall bone loss at the total hip, compared with women with the CC genotype. Serum levels of TGF-beta1 were higher in women with the TT genotype than in those with the CC genotype (46.5 ng/ml vs. 32.3 ng/ml, P = 0.001). These data are clearly in contrast to findings in postmenopausal Japanese women where the CC genotype was associated with higher BMD and decreased bone loss. Further studies are therefore necessary to clarify the relationship between this polymorphism and BMD.

Aged↗
PubMed2001

Regulation of gene expression by nitric oxide.

Nitric oxide (NO) modulates transcription factors that bind specific cis-regulatory DNA responsible for coordinating the spatial and temporal patterns of gene expression that are initiated by a changing microenvironment. In this way NO helps to orchestrate gene transcription and forms the basis of functional cell responses to accommodate metabolic requirements and to coordinate endogenous defense mechanisms against a variety of stress and disease conditions. There is marked overlap between the signalling pathways triggered by NO, superoxide, and hypoxia. Understanding the redox-based regulation of signal transduction and gene expression will provide insights into how cell activities are constantly coordinated and how promising new therapies may be developed.

Animals↗
PubMed2001

Effects of triiodothyronine on the insulin-like growth factor system in primary human osteoblastic cells in vitro.

Thyroid hormone plays a major role in the regulation of bone metabolism but the mechanism by which this is accomplished is not clear. Interactions of thyroid hormone with the growth hormone/insulin-like growth factors (IGFs) axis suggest an alternate pathway of action for triiodothyronine (T(3)) on bone formation, besides direct effects. The present study investigates the influence of T(3) on IGF-1, IGF-2, IGF-1 receptor (IGF-1R), and IGF binding protein (IGFBP) transcripts, and on IGF-1 action in human osteoblastic cells (hOB) under serum-free culture conditions. No influence of T(3) on IGF-1, IGF-2, IGFBP-3, or IGFBP-4 mRNA levels in hOB was observed. However, T(3) at concentrations of 10(-8) mol/L and 10(-7) mol/L increased IGF-1R mRNA levels in a dose-dependent manner (p < 0.01) and enhanced IGFBP-5 mRNA levels at a concentration of 10(-7) mol/L (p < 0.05), as assessed by reverse transcriptase-polymerase chain reaction. Correspondingly, Scatchard analysis of [(125)I]-IGF-1 binding revealed that T(3) at 10(-7) mol/L increased the number of IGF-1 binding sites in hOB, with small changes in receptor affinity. In addition, a synergistic effect of T(3) and IGF-1 on hOB proliferation was found (p < 0.05). We conclude that IGF-1R and IGFBP-5 are thyroid hormone target genes in human osteoblasts, whereas IGF-1 mRNA expression itself appears not to be regulated by T(3) in hOB. However, T(3) stimulates IGF-1R mRNA expression as well as IGF-1 binding and IGF-1 induced cell proliferation in osteoblasts, thus suggesting thyroid hormone may potentiate the effect of IGF-1 at the receptor level. This may contribute to the positive effects of thyroid hormone on bone formation, which, in addition, may be modulated by increased IGFBP-5 expression.

Base Sequence↗
PubMed2001

Expressional regulation of angiopoietin-1 and -2 and the tie-1 and -2 receptor tyrosine kinases during cutaneous wound healing: a comparative study of normal and impaired repair.

It has become evident that a closely regulated presence of vascular endothelial growth factor (VEGF) and angiopoietin (Ang) factors determines the fate of blood vessel formation during angiogenesis. As angiogenesis is central to a normal wound-healing process, we investigated the regulation of Ang-1 and -2 and the related tyrosine kinase with immunoglobulin and epidermal growth factor homology (Tie)-1 and -2 receptors during normal repair in Balb/c mice and diabetes-impaired wound healing conditions in genetically diabetic (db/db) mice. For both normal and impaired healing conditions, we observed a constitutive expression of Ang-1, which was paralleled by an increase of Ang-2 upon injury. Whereas the observed Ang-2 expression declines from Day 7 after injury in control mice, diabetic-impaired healing was characterized by still increasing amounts of Ang-2 at these time points. Furthermore, Tie-1 was strongly induced during repair with a prolonged expression in diabetic mice, whereas Tie-2 expression was constitutive during normal repair but completely absent in diabetes-impaired healing. The overexpression of Ang-2 in the presence of markedly reduced VEGF in wounds of diabetic mice was associated with a dramatic decrease in endothelial cell numbers compared with normal healing as assessed by analysis of the endothelium-specific markers CD31 and von Willebrand factor, whereas the lymphatic endothelium remained stable as determined by expression of VEGF receptor-3 (VEGFR-3/Flt-4).

Angiopoietin-1↗
PubMed2001

Potentiation of cytokine induction of group IIA phospholipase A(2) in rat mesangial cells by ATP and adenosine via the A2A adenosine receptor.

1. In rat mesangial cells extracellular nucleotides were found to increase arachidonic acid release by a cytosolic phospholipase A(2) through the P2Y(2) purinergic receptor. 2. In this study we investigated the effects of ATP and UTP on interleukin-1ss (IL-1ss)-induced mRNA expression and activity of group IIA phospholipase A(2) (sPLA(2)-IIA) in rat mesangial cells. 3. Treatment of cells for 24 h with extracellular ATP potentiated IL-1ss-stimulated sPLA(2)-IIA induction, whereas UTP had no effect. 4. We obtained the following evidence that the P2Y(2) receptor is not involved in the potentiation of sPLA(2)-IIA induction: (i) ATP-gamma-S had no enhancing effect; (ii) suramin, a P(2) receptor antagonist, did not inhibit ATP-mediated potentiation; (iii) inhibition of degradation of extracellular nucleotides by the 5'-ectonucleotidase inhibitor AOPCP did not enhance sPLA(2)-IIA induction and (iv) adenosine deaminase treatment completely abolished the ATP-mediated potentiation of sPLA(2)-IIA induction. 5. In contrast, treatment of mesangial cells with adenosine or the A2A receptor agonist CGS 21680 mimicked the effects of ATP in enhancing IL-1ss-stimulated sPLA(2)-IIA induction, whereas the specific A2A receptor antagonist ZM 241385 completely abolished the potentiating effect of ATP or adenosine. 6. The protein kinase A inhibitor Rp-8-Br-cyclic AMPS dose-dependently inhibited the enhancing effect of ATP or adenosine indicating the participation of an adenosine receptor-mediated cyclic AMP-dependent signalling pathway. 7. These data indicate that ATP mediates proinflammatory long-term effects in rat mesangial cells via its degradation product adenosine through the A2A receptor resulting in potentiation of sPLA(2)-IIA induction.

5'-Nucleotidase↗