Transtemporal ultrasound application potentially elevates brain temperature: results of an anthropomorphic skull model.

PURPOSE: Transtemporal sonothrombolysis is a tool for a more effective treatment in acute stroke patients. However, some reports revealed side effects, which might be potentially connected to temperature elevation. To gain better insight into cerebral temperature changes during transtemporal sonication, diagnostic and therapeutic ultrasound (US) applications were evaluated using an anthropomorphic skull model. MATERIALS AND METHODS: The impact of diagnostic (PW-Doppler, 1.8-MHz, 0.11 W/cm², TIC 1.2) and therapeutic (1-MHz and 3-MHz, 0.07 - 0.71 W/cm², continuous and pulsed mode) US application on temperature changes was evaluated at the level of muscle/temporal bone (TB), TB/brain, brain and at the middle cerebral artery (MCA) using 4 miniature thermocouples along the US beam. Sonication lasted 120 minutes. RESULTS: Diagnostic ultrasound revealed a maximum temperature increase of 1.45°/0.60°/0.39°/0.41°C (muscle/TB, TB/brain, brain, MCA) after 120 minutes. Therapeutic-1-MHz ultrasound raised temperature by 4.33°/2.02°/1.05 °C/0.81°C (pulsed 1:20) and by 10.38°/4.95°/2.43°/2.08°C (pulsed 1:5) over 120 minutes. Therapeutic-3-MHz US raised temperature by 4.89°/2.56°/1.24/1.25°C (pulsed 1:20) and by 14.77°/6.59°/3.56°/2.86°C (pulsed 1:5) over 120 minutes, respectively. Continuous application of therapeutic US (1-MHz and 3-MHz) led to a temperature increase of 13.86°/3.63°/1.66°/1.48°C and 17.09°/4.28°/1.38/0.99°C within 3 minutes. CONCLUSION: Diagnostic PW-Doppler showed only a moderate temperature increase and can be considered as safe. Therapeutic sonication is very powerful in delivering energy so that even pulsed application modes resulted in significant and potentially harmful temperature increases.

Thermal effects of diagnostic ultrasound in an anthropomorphic skull model.

PURPOSE: Exposure to diagnostic ultrasound (US) can significantly heat biological tissue although conventional routine examinations are regarded as safe. The risk of unwanted thermal effects increases with a high absorption coefficient and extended insonation time. Certain applications of transcranial diagnostic US (TC-US) require prolonged exposure. An anthropomorphic skull model (ASM) was developed to evaluate thermal effects induced by TC-US of different modalities. The objective was to determine whether prolonged continuous TC-US application results in potentially harmful temperature increases. MATERIALS AND METHODS: The ASM consists of a human skull with tissue mimicking material and exhibits acoustic and anatomical characteristics of the human skull and brain. Experiments are performed with a diagnostic US device testing four different US modalities: Duplex PW (pulsed wave) Doppler, PW Doppler, color flow Doppler and B-mode. Temperature changes are recorded during 180 minutes of insonation. RESULTS: All measurements revealed significant temperature increases during insonation independent of the US modality. The maximum temperature elevation of + 5.25° C (p < 0.001) was observed on the surface of the skull exposed to duplex PW Doppler. At the bone-brain border a maximum temperature increae of + 2.01 °C (p < 0.001) was noted. Temperature increases within the brain were < 1.23 °C (p = 0.001). The highest values were registered using the duplex PW Doppler modality. CONCLUSION: TC-US induces significant local heating effects in an ASM. An application duration that extends routine clinical periods causes potentially harmful heating especially in tissue close to bone. TC-US elevates the temperature in the brain mimicking tissue but is not capable of producing harmful temperature increases during routine examinations. However, the risk of thermal injury in brain tissue increases significantly after an exposure time of > 2 hours.

The inflammatory mediator oncostatin M induces angiopoietin 2 expression in endothelial cells in vitro and in vivo.

OBJECTIVES: Members of the glycoprotein 130 (gp130) receptor-gp130 ligand family play a role in angiogenesis in different tissues. We tested the effect of this cytokine family on the angiopoietin (Ang)-Tie system, which is involved in blood vessel maturation, stabilization, and regression. RESULTS: Oncostatin M (OSM) increased Ang2 expression in human umbilical vein endothelial cells via Janus kinase/signal transducer and activator of transcription (JAK/STAT) and mitogen-activated protein (MAP) kinase activation. Furthermore, OSM induced Ang2 expression in macrovascular endothelial cells isolated from the human aorta and in microvascular endothelial cells isolated from human heart. Our in vivo experiments revealed that mRNA expression of Ang2 in hearts of mice injected with OSM increased significantly, and levels of OSM mRNA significantly correlated with mRNA levels of Ang2 in human hearts. In addition, OSM increased the expression of its own receptors, gp130 and OSM receptor, in endothelial cells in vitro and in mice in vivo, and levels of OSM mRNA significantly correlated with mRNA levels of gp130 and OSM receptor in human hearts. CONCLUSION: Our data, showing the effects of OSM on the Ang-Tie system in endothelial cells, in hearts of mice, and in human heart tissue, provide yet another link between inflammation and angiogenesis.

The inflammatory mediator oncostatin M induces stromal derived factor-1 in human adult cardiac cells.

Stromal derived factor 1 (SDF-1) is a CXC chemokine important in the homing process of stem cells to injured tissue. It has been implicated in healing and tissue repair. Growing evidence suggests that the glycoprotein-130 (gp130) ligand family is involved in repair processes in the heart. The aim of our study was to determine whether gp130 ligands could affect SDF-1 expression in cardiac cells. Human adult cardiac myocytes (HACMs) and fibroblasts (HACFs) were treated with gp130 ligands. Protein and mRNA levels of SDF-1 were determined using ELISA and RT-PCR, respectively. mRNA levels of SDF-1 were determined in human and mouse heart samples by RT-PCR. HACMs and HACFs constitutively express SDF-1, which was significantly up-regulated by the gp130 ligand oncostatin M (OSM). This effect was counteracted by a p38 inhibitor and to a lesser extent by a PI3K inhibitor. mRNA expression of SDF-1 in hearts of mice injected with OSM increased significantly. Levels of OSM and SDF-1 mRNA correlated significantly in human failing hearts. Our data, showing that OSM induces SDF-1 protein secretion in human cardiac cells in vitro and murine hearts in vivo, suggest that OSM via the induction of SDF-1 might play a key role in repair and tissue regeneration.

Macrophage colony stimulating factor expression in human cardiac cells is upregulated by tumor necrosis factor-alpha via an NF-kappaB dependent mechanism.

INTRODUCTION: Macrophage colony stimulating factor (M-CSF) is a key factor for monocyte and macrophage survival and proliferation. M-CSF has been implicated in cardiac healing and repair after myocardial infarction. METHODS AND RESULTS: We show by immunohistochemistry and Western blotting analysis that M-CSF protein is present in human heart tissue. Cultured human adult cardiac myocytes (HACM) and human adult cardiac fibroblasts (HACF) isolated from human myocardial tissue constitutively express M-CSF. When HACM and HACF were treated with tumor necrosis factor-alpha (TNF-alpha) M-CSF protein production and M-CSF mRNA expression, determined by ELISA or by using RT-PCR, respectively, was significantly increased. To determine a possible role of nuclear factor kappaB (NF-kappaB) and activating protein 1 (AP-1) in M-CSF regulation, blockers to both pathways and an adenovirus overexpressing a dominant negative (dn) form of IkappaB kinase 2 (IKK2) were used. Only the NF-kappaB blocker dimethylfumarate and the dn IKK2, but not januskinase inhibitor-1 (JNK-I), were able to block the TNF-alpha-induced increase in M-CSF production in these cells, suggesting that the induction of M-CSF through TNF-alpha is mainly dependent on the activation of the NF-kappaB pathway. The monocyte activation marker CD11b was significantly increased after incubating U937 cells with conditioned medium from HACM or HACF as determined by FACS analysis. CONCLUSIONS: Our in vitro data taken together with our immunohistochemistry data suggest that human cardiac cells constitutively express M-CSF. This expression of M-CSF in the human heart and its upregulation by TNF-alpha might contribute to monocyte and macrophage survival and differentiation.

Vascular endothelial growth factor is induced by the inflammatory cytokines interleukin-6 and oncostatin m in human adipose tissue in vitro and in murine adipose tissue in vivo.

OBJECTIVES: It is believed that adipose tissue acts as an endocrine organ by producing inflammatory mediators and thereby contributes to the increased cardiovascular risk seen in obesity. A link between adipose tissue mass and angiogenesis has been suggested. Vascular endothelial growth factor (VEGF) seems to be implicated in this process. Members of the glycoprotein (gp)130 ligand family regulate VEGF expression in other cells. METHODS AND RESULTS: We used tissue explants as well as primary cultures of preadipocytes and adipocytes from human subcutaneous and visceral adipose tissue to investigate whether the gp130 ligands oncostatin M (OSM), interleukin-6 (IL-6), leukemia inhibitory factor (LIF), and cardiotrophin-1 (CT-1) regulate VEGF expression in human adipose tissue. Human subcutaneous and visceral adipose tissue responded to treatment with IL-6 and OSM with a significant increase in VEGF production. Human preadipocytes were isolated from subcutaneous and visceral adipose tissue. Adipocyte-differentiation was induced by hormone-supplementation. All cell types responded to IL-6 and OSM with a robust increase in VEGF protein production and a similar increase in VEGF-specific mRNA. Furthermore, IL-1beta synergistically enhanced the effect of OSM on VEGF production. AG-490, a JAK/STAT inhibitor, abolished the OSM-dependent VEGF induction almost completely. In mice, IL-6 and OSM increased serum levels of VEGF and VEGF mRNA and vessel density in adipose tissue. CONCLUSION: We speculate that the inflammatory cytokines IL-6 and OSM might support angiogenesis during adipose tissue growth by upregulating VEGF.

No evidence for a direct role of Helicobacter pylori and Mycoplasma pneumoniae in carotid artery atherosclerosis.

BACKGROUND: That infections with certain pathogens, by initiating an inflammatory response, may contribute to the development of atherosclerosis is suggested by clinical and experimental evidence. AIM: To analyse atherosclerotic plaques of the carotid artery, samples of apparently healthy greater saphenous veins and circulating leucocytes from the same individual patients for the presence of Helicobacter pylori and Mycoplasma pneumoniae. METHODS: Samples from 36 patients undergoing carotid endarterectomy for symptomatic carotid artery stenosis were analysed by polymerase chain reaction for the presence of DNA specific for H. pylori and M. pneumoniae. IgG antibody titres against H. pylori and M pneumoniae and plasma levels of soluble E-selectin, soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1 were determined. RESULTS: M. pneumoniae-specific DNA was detected in the atherosclerotic plaques of 13 of 36 (36.1%) patients, in the saphenous veins of 9 of 36 (25%) patients and in the leucocytes of 27 of 36 (75%) patients. No salient association was observed between the presence of M. pneumoniae-specific DNA in leucocytes and atherosclerotic plaques or veins. A marked correlation between the presence of M. pneumoniae in the respective specimens and the studied inflammatory markers or the presence of anti-M. pneumoniae antibodies was not observed. H. pylori-specific DNA could not be detected in the specimens tested. CONCLUSIONS: The absence of H. pylori and the random distribution of M. pneumoniae in tissue samples obtained from patients with symptomatic carotid artery stenosis do not support a role for these pathogens in the development of atherosclerosis due to a direct interaction of the bacteria with the vasculature.

The gp130 ligand oncostatin M regulates tissue inhibitor of metalloproteinases-1 through ERK1/2 and p38 in human adult cardiac myocytes and in human adult cardiac fibroblasts: a possible role for the gp130/gp130 ligand system in the modulation of extracellular matrix degradation in the human heart.

There is ample evidence supporting the view that alterations in the balance between matrix deposition and matrix degradation brought about by changes in the respective activities of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) contribute significantly to cardiac dysfunction and disease. Here we show that TIMP-1 was upregulated up to threefold after treatment with the inflammatory mediator and gp130 ligand oncostatin M (OSM) in human adult cardiac myocytes and fibroblasts. The Erk1/2 inhibitor PD98059 and the p38 inhibitor SD202190 abolished the effect of OSM on TIMP-1 production in both cell types. Human cardiac myocytes and human cardiac fibroblasts also express MMP-1, 2, 3 and 9, and TIMP-2 constitutively. OSM, however, did not affect the expression of these proteins. In addition also the other gp130 ligands tested, cardiotrophin-1 (CT-1), interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) had no effect on the expression of TIMPs and MMPs studied. We speculate that OSM by inducing TIMP-1 expression counteracts excessive proteolysis and unrestricted matrix degradation during inflammatory processes in the heart. The notion that OSM favors matrix stabilization in the human heart is further supported by our earlier observation that OSM also upregulates PAI-1, the physiological inhibitor of the protease urokinase-type PA (u-PA), which in turn is essential for extracellular proteolysis. Therefore we propose a role for the gp130 ligand OSM in the modulation of cardiac remodeling and repair processes.