Biomedical subjects

Frank Rose

Publications and source records attributed to Frank Rose.

At least 19 recordsLinked to original sources

PubMed2006

Accuracy of single-session extracranial radiotherapy for simple shaped lung tumor or metastasis using fast 3-D CT treatment planning.

BACKGROUND: This study is situated in the area of measuring set-up accuracy and time periods of single-session extracranial radiotherapy (SSRT) for simple-shaped targets (e.g., spherical or rotational symmetrical) definitively located in the peripheral lung. METHODS AND MATERIALS: After adaptation of the stereotactic body frame, the patient has to remain in the vacuum pillow during planning computed tomography (CT), fast three-dimensional (3-D) treatment planning, and direct irradiation after verification. Fast preplanning is performed by using virtual simulation software to accelerate the method. RESULTS: In our new procedure, SSRT is applied in approximately 1.5 h. The mean setup accuracy vector was 2.4+/-0.7 mm in the range of 1.34 to 4 mm. Mean intrafractional patient movement in the stereotactic body frame before and after radiation was 0.70 mm+/-0.5 mm and 0.76+/-0.76 mm in the range of 0 to 2.8 mm. Mean time period steps were measured at (1) planning CT with 3-D treatment planning: 76+/-12 min; (2) irradiation and verification: 33+/-7 min; and (3) complete procedure duration: 109+/-11 min (range, 89-169). CONCLUSIONS: The main difference between the positioning technique of SSRT and that of conventional extracranial radiosurgery is the tighter patient fixation, which guarantees minimal patient movement. The main advantages are procedure acceleration and omission of CT simulation. SSRT is a preliminary stage of real-time treatment.

Aged↗

PubMed2006

Human RELMbeta is a mitogenic factor in lung cells and induced in hypoxia.

RELMbeta (resistin-like molecule) represents the most related human homologue of mouse RELMalpha, also known as hypoxic-induced mitogenic factor (HIMF). In this study, we isolated RELMbeta cDNA from human lung tissue and performed regulatory and functional expression studies. RELMbeta mRNA was upregulated in hypoxia in human lung A549 cell line as well as primary cultured adventitial fibroblasts and smooth muscle cells (SMC) of pulmonary arteries. Upon transfection of a RELMbeta encoding expression plasmid into these cells, we observed significant induction of proliferation particularly in SMC and A549 cells, which could be blocked by phosphatidyl-inositol 3-kinase (PI3K) inhibitors LY294002 and wortmannin. The results suggest that human RELMbeta may contribute to hypoxic-induced pulmonary vascular remodeling processes or hypoxia related fibrotic lung disease.

Androstadienes↗

PubMed2006

Circulating adrenomedullin in obstructive sleep apnoea.

Adrenomedullin (AM) is a potent endothelial-derived vasodilator secreted under the influence of various stimuli such as hypoxia, shear stress and cytokines. As all of these stimuli might be active under the conditions of obstructive sleep apnoea (OSA), we hypothesized that vascular AM production is increased in these patients. The study included 41 consecutive OSA patients and 28 control subjects without sleep-disordered breathing who were recruited from a pool of patients hospitalized for other reasons. Both groups were matched for anthropometric and comorbid factors. In all patients, i.e. OSA and controls, peripheral venous blood samples were taken at 07:00 hours after diagnostic polysomnography. In subsets of OSA patients, this was repeated after two nights of continuous positive airway pressure (CPAP) therapy (n = 28) and after several months of constant CPAP use (n = 11). The controls and the untreated OSA patients did not have serial blood sampling. In all blood samples, plasma AM levels were measured by an enzyme immunoassay kit. At baseline, the OSA patients had markedly elevated AM concentrations when compared to the controls. There were no differences between normo- and hypertensive OSA patients. After two nights of CPAP therapy, AM levels significantly decreased. Patients on long-term CPAP treatment showed complete normalization of plasma AM concentrations. In conclusion, this pilot study suggests that circulating AM is increased in untreated OSA irrespective of coexistent arterial hypertension and declines after CPAP therapy. AM upregulation might be considered as an adaptive mechanism to counteract the emergence of OSA-related cardiovascular disease.

Adrenomedullin↗

PubMed2005

Impact of HIF-1alpha and HIF-2alpha on proliferation and migration of human pulmonary artery fibroblasts in hypoxia.

Proliferation of adventitial fibroblasts of small intrapulmonary arteries (FBPA) has been disclosed as an early event in the development of pulmonary hypertension and cor pulmonale in response to hypoxia. We investigated the role of hypoxia-inducible transcription factors (HIF) in human FBPA exposed to hypoxia. Primary cultures of FBPA displayed a strong mitogenic response to 24 h hypoxia, whereas the rate of apoptosis was significantly suppressed. In addition, the migration of FBPA was strongly increased under hypoxic conditions but not the expression of alpha-smooth muscle actin. Hypoxia induced a marked up-regulation (protein level) of both HIF-1alpha and HIF-2alpha, alongside with nuclear translocation of these transcription factors. Specific inhibition of either HIF-1alpha or HIF-2alpha was achieved by RNA interference technology, as proven by HIF-1alpha and HIF-2alpha mRNA and protein analysis and expression analysis of HIF downstream target genes. With the use of this approach, the hypoxia-induced proliferative response of the FBPA was found to be solely HIF-2alpha dependent, whereas the migratory response was significantly reduced by both HIF-1alpha and HIF-2alpha interference. In conclusion, HIF up-regulation is essential for hypoxic cellular responses in human pulmonary artery adventitial fibroblasts such as proliferation and migration, mimicking the pulmonary hypertensive phenotype in vivo. Differential HIF subtype dependency was noted, with HIF-2alpha playing a predominant role, which may offer future intervention strategies.

Actins↗

PubMed2005

Epidermal fatty acid-binding protein is increased in rat lungs following in vivo treatment with keratinocyte growth factor.

Exogenous application of keratinocyte growth factor protects the lung against a variety of injurious stimuli. KGF-treatment leads to pronounced hyperplasia of alveolar epithelial type II cells and to stabilization of surfactant homeostasis after lung injury. Epidermal fatty acid-binding protein is involved in the synthesis of surfactant phospholipids and acts as an antioxidant scavenging reactive lipids. We treated adult rats with recombinant human keratinocyte growth factor (Palifermin) via intratracheal instillation and analyzed the expression of epidermal fatty acid-binding protein mRNA and protein by quantitative RT-PCR, immunoblotting as well as immunohistochemistry. Keratinocyte growth factor-treatment in vivo leads to an increased expression of epidermal fatty acid-binding protein mRNA and protein in the total lung. Epidermal fatty acid-binding protein mRNA expression per alveolar epithelial type II cell remains constant as shown in isolated type II cells. Epidermal fatty acid-binding protein immunoreactivity is seen in most if not all hyperplastic alveolar epithelial type II cells, and is mainly localized to the cytoplasm. The increase in epidermal fatty acid-binding protein gene expression associated with type II cell hyperplasia might contribute to the molecular mechanisms mediating lung protection by keratinocyte growth factor.

Animals↗

PubMed2005

Identification of novel Nox4 splice variants with impact on ROS levels in A549 cells.

NAD(P)H oxidases (Nox) generate reactive oxygen species (ROS) that function in host defense and cellular signaling. While analyzing the expression of Nox4 at the protein and the mRNA levels, we identified four novel Nox4 splice-variants Nox4B, Nox4C, Nox4D, and Nox4E, which are expressed in human lung A549 cell line and lung tissues. One Nox4 isoform lacks the first NAD(P)H binding site (Nox4B) while another lacks all FADH and NAD(P)H binding sites (Nox4C). Cells over-expressing NoxB or Nox4C exhibited a decrease in ROS levels. Thus, these isoforms have dominant negative characteristics for ROS generation. Two other splice-variants (Nox4D, Nox4E) lack the transmembrane domains, suggesting these as non-membrane associated isoforms. Nox4D contains all FADH and NAD(P)H binding domains and shows the same rate of ROS generation as Nox4 prototype. Taken together, we suggest that Nox4 exists as several isoforms that may have different functions in ROS-related cell signaling.

Alternative Splicing↗

PubMed2005

Hypoxia-driven proliferation of human pulmonary artery fibroblasts: cross-talk between HIF-1alpha and an autocrine angiotensin system.

Pulmonary artery adventitial fibroblasts (FBPA) may play a central role in lung vascular remodeling under conditions of hypoxia and inflammation, the result being pulmonary hypertension and cor pulmonale. In cultured human FBPA, both angiotensin II (Ang II) and hypoxia promoted cell cycle progression and cell proliferation and suppressed apoptosis. These effects were further enhanced when both stimuli were applied simultaneously. Hypoxia elevated the expression of hypoxia-inducible factor 1alpha (HIF-1alpha) and increased the expression of genes regulated by the hypoxia-responsive element (HRE). Up-regulation of both angiotensin-converting enzyme (ACE) and Ang II receptor type 1 (AT1) was also observed. Exogenous Ang II further increased HIF/HRE-dependent signaling in FBPA, whereas suppression of the autocrine ACE-Ang II-AT1 loop with inhibitors of ACE, AT1, and phosphatidylinositol 3-kinase (PI3K) reduced the proliferative response to both hypoxia and exogenous Ang II. Overexpression of HIF-1alpha by transient transfection caused the same proliferative effect and up-regulation of AT1 expression that were observed under hypoxic conditions. In contrast, small interfering RNA targeting HIF-1alpha inhibited hypoxia-induced ACE and AT1 expression. Our studies indicate that the ACE-Ang II-AT1 system serves as a positive feedback loop and fosters FBPA proliferation under hypoxic conditions, with the PI3K-HIF-HRE axis as the central effector pathway. This pathway may thus facilitate vascular remodeling under hypoxic conditions.

Angiotensin II↗

PubMed2005

Role of hypoxia-inducible factor-1alpha in hypoxia-induced apoptosis of primary alveolar epithelial type II cells.

Hypoxia affects alveolar homeostasis and may induce epithelial injury, which has been implicated in lung diseases such as fibrosis. The underlying cellular and molecular mechanisms are, however, largely unknown. Primary rat alveolar epithelial type II cells (ATII) exposed to graded hypoxia for 24 and 48 h caused a dose-dependent induction of cell cycle arrest and suppression of proliferation, which were comparable to the effects of angiotensin II, a potent inducer of ATII cell death. Hypoxia-induced changes in ATII homeostasis are thought to proceed primarily via activation of hypoxia inducible-factor (HIF)-1alpha, because hypoxia increased HIF-1alpha protein expression, nuclear translocation, and transactivation of its specific DNA binding domain, the hypoxia responsive element (HRE). Under hypoxic conditions, expression of the proapoptotic protein Bnip3L, which belongs to the Bcl 2 family and is known to be one of the HIF-1-dependent target genes, was upregulated. Suppression of HIF-1alpha or Bnip-3L with small interfering RNA (siRNA) fully blocked the hypoxia-induced apoptosis and Bnip3L expression. In line with these data, overexpression of HIF-1alpha by transient transfection enhanced the hypoxia-induced apoptosis. Thus, we conclude that hypoxia suppresses alveolar epithelial cell proliferation and enhances ATII apoptosis through activation of the HIF-1alpha/HRE axis and a mechanism that involves Bnip3L. Targeting HIF-1alpha may represent a new strategy that could impede the alveolar denudation that is observed in several lung diseases.

Animals↗

PubMed2005

Analysis of tumor vessel supply in Lewis lung carcinoma in mice by fluorescent microsphere distribution and imaging with micro- and flat-panel computed tomography.

In lung carcinomas the blood supply varies depending on tumor type and stage and can develop from pulmonary or bronchial circulation, or both. To examine this in vivo, primary bronchogenic Lewis lung carcinoma cells were intratracheally instilled in C57BL/6 mice. Within 7 days, histological examinations showed progressive tumor growth at the peripheral parenchymal region. The relative contribution of tumor blood supply via the pulmonary and systemic arteries was studied in detail using fluorescent microspheres (10 microm). When compared to healthy lung parenchyma (13:1), Lewis lung carcinoma tumor tissue (52:1) showed a fourfold increase in pulmonary to systemic microspheres, indicating that the pulmonary arteries are the predominant tumor-feeding vessels. After filling the vessels with a vascular cast, the microanatomy of vessels being derived from the pulmonary artery was visualized with micro computed tomography. Flat-panel volumetric computed tomography provided longitudinal visualization of tissue bridges between the growing tumor and the pulmonary vasculature. In this model of peripheral parenchymal malignancy, new imaging techniques allowed effective visualization of lung tumor growth and vascularization in living mice, demonstrating a pulmonary blood supply for lung tumors.

Animals↗

PubMed2005

Potential applications of flat-panel volumetric CT in morphologic and functional small animal imaging.

Noninvasive radiologic imaging has recently gained considerable interest in basic and preclinical research for monitoring disease progression and therapeutic efficacy. In this report, we introduce flat-panel volumetric computed tomography (fpVCT) as a powerful new tool for noninvasive imaging of different organ systems in preclinical research. The three-dimensional visualization that is achieved by isotropic high-resolution datasets is illustrated for the skeleton, chest, abdominal organs, and brain of mice. The high image quality of chest scans enables the visualization of small lung nodules in an orthotopic lung cancer model and the reliable imaging of therapy side effects such as lung fibrosis. Using contrast-enhanced scans, fpVCT displayed the vascular trees of the brain, liver, and kidney down to the subsegmental level. Functional application of fpVCT in dynamic contrast-enhanced scans of the rat brain delivered physiologically reliable data of perfusion and tissue blood volume. Beyond scanning of small animal models as demonstrated here, fpVCT provides the ability to image animals up to the size of primates.

Animals↗

PubMed2005

HIF-1alpha attenuates tumor growth in spite of augmented vascularization in an A549 adenocarcinoma mouse model.

The hypoxia-inducible transcription factor, HIF-1, adapts cells to low oxygen tension. In addition to the activation of angiogenesis by induction of VEGF, HIF-1 may trigger hypoxia-induced growth arrest and apoptosis. The aim of this study was to analyze the overall effect of HIF-1 on tumor growth in a mouse model, employing human lung adenocarcinoma A549 cells. The A549 cells were transfected to overexpress HIF-1alpha. These cells displayed decreased proliferation, cell-cycle entry, colony formation in soft agar and elevated levels of apoptosis, when compared to control cells transfected with empty vector. The cells were employed in a tumor model by subcutaneous injection into CD-1 nude mice. Persistent overexpression of HIF1alpha and VEGF was demonstrated in these tumors. The HIF-1alpha-overexpressing tumors displayed less tumor growth when compared to tumors formed by control cells. Tumors derived from HIF-1alpha-overexpressing cells revealed an increase in apoptosis when compared to control tumors, in spite of a marked increase in vascular density. We conclude that in lung A549 cells, overexpression of HIF-1alpha negatively affects tumor growth due to decreased proliferation and increased apoptosis, despite augmented angiogenesis.

Adenocarcinoma↗

PubMed2004

Upregulation of NAD(P)H oxidase 1 in hypoxia activates hypoxia-inducible factor 1 via increase in reactive oxygen species.

Hypoxia sensing and related signaling events, including activation of hypoxia-inducible factor 1 (HIF-1), represent key features in cell physiology and lung function. Using cultured A549 cells, we investigated the role of NAD(P)H oxidase 1 (Nox1), suggested to be a subunit of a low-output NAD(P)H oxidase complex, in hypoxia signaling. Nox1 expression was detected on both the mRNA and protein levels. Upregulation of Nox1 mRNA and protein occurred during hypoxia, accompanied by enhanced reactive oxygen species (ROS) generation. A549 cells, which were transfected with a Nox1 expression vector, revealed an increase in ROS generation accompanied by activation of HIF-1-dependent target gene expression (heme oxygenase 1 mRNA, hypoxia-responsive-element reporter gene activity). In A549 cells stably overexpressing Nox1, accumulation of HIF-1alpha in normoxia and an additional increase in hypoxia were noted. Interference with ROS metabolism by the flavoprotein inhibitor diphenylene iodonium (DPI) and catalase inhibited HIF-1 induction. This suggests that H2O2 links Nox1 and HIF-1 activation. We conclude that hypoxic upregulation of Nox1 and subsequently augmented ROS generation may activate HIF-1-dependent pathways.

Catalase↗

PubMed2004

Basic features of hypoxic pulmonary vasoconstriction in mice.

Hypoxic pulmonary vasoconstriction (HPV) matches lung perfusion with ventilation which tends to optimize pulmonary gas exchange. Investigations using genetically engineered mice represent a promising approach to understand the underlying mechanisms. Our goal was to characterize basic features of HPV in the isolated buffer-perfused and ventilated mouse lung system. HPV was reproducible for several hours when ventilating the lungs with 1% O2 (10 min) alternated with normoxic ventilation periods (21% O2, 15 min). HPV was well elicitable and most constant using Krebs-Henseleit buffer with the addition of hydroxyethylamylopectin as an oncotic agent. Inhibition of both lung NO and prostanoid formation amplified HPV in an over-additive fashion. HPV was higher in BALB/c mive as compared to C57BL/6 mice, and was approximately threefold enhanced under positive pressure ventilation as compared to negative pressure ventilation. A three hour hypoxic ventilation period resulted in a biphasic vasoconstrictor response with loss of posthypoxic vasodilatation. In summary, we have characterised HPV and established an experimental set-up optimized for investigation of the basic mechanisms of HPV in mice.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2004

Prostacyclin and its analogues in the treatment of pulmonary hypertension.

Prostacyclin and its analogues (prostanoids) are potent vasodilators and possess antithrombotic and antiproliferative properties. All of these properties help to antagonize the pathological changes that take place in the small pulmonary arteries of patients with pulmonary hypertension. Indeed, several prostanoids have been shown to be efficacious to treat pulmonary hypertension, while the main mechanism underlying the beneficial effects remains unknown. There are indications of beneficial combination effects of prostaglandins and phosphodiesterase inhibitors and endothelin receptor antagonists. This speaks in favor of combination therapies for pulmonary hypertension in the future. The mode of application of prostanoids used in randomized controlled studies has been quite variable: continuous i.v. infusion of prostacyclin, continuous s.c. infusion of treprostinil, p.o. application of beraprost, and inhaled application of iloprost. In addition, the applied doses were quite different, ranging from 0.25 ng/kg/min for inhaled iloprost to 30-50 ng/kg/min for i.v. prostacyclin. While the principal pharmacological properties of all prostanoids are very similar due to a main action on IP receptors, there are considerable differences in pharmacokinetics and metabolism, with half-lives of 2 min for prostacyclin and about 34 min for treprostinil for i.v. infused drugs and half-lives of about 85 min for s.c. infused treprostinil. In addition, the adverse effects largely depend on the doses used and the mode of application, although there is great variability between subjects. It remains to be determined which patients will profit most from which substance (or combination) and mode of application.

Epoprostenol↗

PubMed2004

Reversal of nocturnal periodic breathing in primary pulmonary hypertension after lung transplantation.

Nocturnal periodic breathing (PB) closely resembling Cheyne-Stokes respiration in congestive heart failure has been reported to occur in end-stage primary pulmonary hypertension (PPH). We herein describe the clinical course of a 56-year-old female patient with PPH and severe hypoxemia, hypocapnia, and right ventricular compromise in whom sleep-disordered breathing (SDB) resolved after successful double-lung transplantation. This case illustrates the crucial roles of blood gas alterations and hemodynamic impairment in the emergence of PB in PPH, and is in favor of a genuine association between advanced right heart failure and the development of SDB.

Cheyne-Stokes Respiration↗

PubMed2003

RNA interference for HIF-1alpha inhibits its downstream signalling and affects cellular proliferation.

Transcription factor HIF-1 is a key determinant of oxygen-dependent gene regulation. Suppression of HIF-1alpha is important for exploring HIF-1-dependent processes and for interfering with hypoxia-induced pathophysiological events. This study applied RNA-interference targeting HIF-1alpha to the human lung A549 cell line. Transfection of HIF-1alpha-siRNA reduced HIF-1alpha synthesis as measured on mRNA and protein level by realtime RT-PCR, Western blot, and immuncytochemistry. A time kinetic for hypoxic stabilization of HIF-1alpha protein and its inhibition by HIF-1alpha-siRNA is included. Hypoxic induction of HIF-1-controlled target genes as heme oxygenase I (HO-1), phosphoglycerate kinase (PGK), and vascular endothelial growth factor (VEGF) was markedly attenuated by HIF-1alpha-siRNA treatment. Correspondingly, gene activation via hypoxia-responsive-element, as shown by reporter gene assay, was inhibited by HIF-1alpha-siRNA. Moreover, this approach was found to suppress the shift from from S-phase to G1-phase observed in A549 cells in response to hypoxia, supporting a role of HIF-1alpha in oxygen-dependent cell cycle regulation.

Cell Division↗

PubMed2003

Chronic sildenafil treatment inhibits monocrotaline-induced pulmonary hypertension in rats.

Sildenafil, a phosphodiesterase 5 inhibitor, is currently under investigation for therapy of pulmonary hypertension. This study was designed to investigate chronic effects of sildenafil in monocrotaline (MCT)-induced pulmonary hypertension in rats. Four weeks after a single subcutaneous injection of MCT, the animals displayed nearly threefold elevated pulmonary artery pressure and vascular resistance values, with a concomitant decline in central venous oxygen saturation and arterial oxygenation. Marked right heart hypertrophy was evident, and massive thickening of the precapillary artery smooth muscle layer was histologically apparent. Further deterioration of pulmonary hypertension occurred 6 weeks after MCT injection, with some animals dying during this period because of right heart failure. When chronically administered from Days 14-28, sildenafil significantly increased plasma cyclic guanosine monophosphate and inhibited the development of pulmonary hypertension and right heart hypertrophy, with preservation of gas exchange and systemic arterial pressure. A corresponding efficacy profile was also noted for long-term feeding with sildenafil from Days 28-42. Moreover, the death rate significantly decreased in those animals treated with sildenafil. We conclude that sildenafil attenuates MCT-induced pulmonary hypertension and cor pulmonale in rats.

Administration, Oral↗

PubMed2003

Oral sildenafil as long-term adjunct therapy to inhaled iloprost in severe pulmonary arterial hypertension.

OBJECTIVES: We sought to investigate the impact of adjunct sildenafil on exercise capacity and hemodynamic parameters in patients with pulmonary arterial hypertension (PAH) who fulfilled predefined criteria of deterioration despite ongoing treatment with inhaled iloprost. BACKGROUND: Inhaled iloprost is an effective therapy in PAH. The phosphodiesterase-5 inhibitor sildenafil exerts pulmonary vasodilation and may amplify prostanoid efficacy. METHODS: Of 73 PAH patients receiving long-term inhaled iloprost treatment, 14 fulfilled criteria of deterioration unresponsive to conventional treatment. These patients received adjunct oral sildenafil over a period of nine to 12 months, leaving the inhalative iloprost regimen unchanged. RESULTS: Before iloprost therapy, the baseline 6-min walking distance was 217 +/- 31 m (mean +/- SEM), with an improvement to 305 +/- 28 m within the first three months of iloprost treatment and a subsequent decline to 256 +/- 30 m after 18 +/- 4 months. Adjunct therapy with sildenafil reversed the deterioration and increased the 6-min walk distance to 346 +/- 26 m (p = 0.002, Wilcoxon test) at three months of combined therapy, with a sustained efficacy up to 12 months (349 +/- 32 m, p = 0.002). The distribution of New York Heart Association functional classes (IV/III/II) improved from September 9, 2000, before sildenafil, to January 8, 2003, after nine to 12 months with sildenafil. All hemodynamic variables changed favorably: pulmonary vascular resistance decreased from 2,494 +/- 256 before sildenafil to 1,950 +/- 128 dynes.s.cm(-5).m(2) after three months of adjunct sildenafil (p = 0.036). Two patients died of severe pneumonia during the period of combined therapy. No further serious adverse events occurred. CONCLUSIONS; In patients with severe PAH deteriorating despite ongoing prostanoid treatment, long-term adjunct oral sildenafil improves exercise capacity and pulmonary hemodynamics. A combination of prostanoids and sildenafil is an appealing concept for future treatment of pulmonary hypertension.

3',5'-Cyclic-GMP Phosphodiesterases↗