In JoVE (2)

Other Publications (45)

Articles by Rainer Meyer in JoVE

 JoVE Medicine

A Model to Simulate Clinically Relevant Hypoxia in Humans

1Department of Anaesthesiology and Intensive Care Medicine, University Hospital of Bonn, 2Institute of Clinical Chemistry and Clinical Pharmacology, University of Bonn, 3Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, 4Institute of Physiology 2, University of Bonn


JoVE 54933

Other articles by Rainer Meyer on PubMed

Estrogenic Hormone Action in the Heart: Regulatory Network and Function

Cardiovascular Research. Feb, 2002  |  Pubmed ID: 11861041

Cardiovascular diseases are the leading cause of death in the industrialised countries and display significant gender-based differences. Estrogen plays an important role in the pathogenesis of heart disease and is able to modulate the progression of cardiovascular disease. The focus on the beneficial influence of estrogen is gradually shifting from the vascular system to the myocardium. The presence of functional estrogen receptors in the myocardium has been demonstrated. Estrogen is important for cardiovascular baseline physiology and modulates the myocardial response under pathological conditions. Here we summarise the current knowledge of the regulatory network of estrogenic action in the myocardium and its effects on cardiovascular function.

Neopterin Inhibits ATP-induced Calcium Release in Alveolar Epithelial Cells in Vitro

Mediators of Inflammation. Jun, 2002  |  Pubmed ID: 12137247

Serum neopterin concentrations rise during activation of the cellular immune system. It is suggested that neopterin interacts with cellular redox mechanisms. This induces oxidative stress, which inhibits intracellular Ca2+ transients in various cell types. In type II alveolar epithelial cells, Ca2+ increase is considered involved in the exocytosis of surfactants. This exocytosis is disturbed during inflammation.

Induction of Atrial Fibrillation in Mice by Rapid Transesophageal Atrial Pacing

Basic Research in Cardiology. Nov, 2002  |  Pubmed ID: 12395207

Atrial fibrillation (AF) as an "indicator arrhythmia" for enhanced atrial vulnerability in mouse hearts has not yet been systematically examined. We therefore evaluated a transesophageal rapid atrial stimulation protocol for the induction of AF in C57Bl/6 mice.

Increasing Myocardial Contraction and Blood Pressure in C57BL/6 Mice During Early Postnatal Development

American Journal of Physiology. Heart and Circulatory Physiology. Feb, 2003  |  Pubmed ID: 12414444

Knowledge of the developmental changes of cardiovascular parameters in the genetic background of a mouse strain is important for understanding phenotypic changes in transgenic or knockout mouse models for heart disease. We studied arterial blood pressure and myocardial contractility in mice of the common background strain C57BL/6, aged 21 days [postnatal day 21 (P21)] to 580 days. Heart rate increased during maturation from 396 beats/min at P21 to 551 beats/min at postnatal day 50 (P50), and mean arterial blood pressure increased in parallel from 86 to 110 mmHg and remained constant afterward. Echocardiographically determined left ventricular myocardial wall dimensions (R = 0.79, P < 0.0001) and left ventricular mass calculated using the area-length algorithm correlated strongly with histomorphometrical measurements (R = 0.93, P < 0.001). Sarcomere shortening records from isolated ventricular myocytes used as a measure for myocardial contractility revealed a negative shortening-frequency relation under a pacing frequency of 2 Hz and a positive relation above 2 Hz. Shortening amplitudes recorded from P21 myocytes were smaller, and the shortening-frequency relation was less steep than in adult myocytes. A stimulation pause was followed by a negative "staircase" at pacing frequency of < or =6 Hz and a positive staircase at > or =6 Hz. P21 myocytes developed positive staircases at 8 and 10 Hz, and adult myocytes also developed them at 6 Hz. Blood pressure increase during maturation until P50 may originate from increasing single cardiomyocyte contractility.

17 Beta-estradiol Regulates the Expression of Endothelin Receptor Type B in the Heart

British Journal of Pharmacology. Sep, 2003  |  Pubmed ID: 12967949

(1) Little is known about the interaction of 17beta-estradiol (E2) and the vasoactive endothelin system in the heart. Endothelin signaling is activated in a failing heart and may contribute to myocardial dysfunction and remodeling. Therefore, we investigated the regulation of proteins of the endothelin system (ppET-1, ECE and ETA-R and ETB-R) in the hearts of female spontaneously hypertensive rats (SHR) with respect to E2. (2) Relative expression levels of the respective cardiac mRNA obtained from sham-operated, ovariectomized and ovariectomized E2-substituted SHR were quantified by real-time PCR. Ovariectomy led to a significant upregulation of the ETB-R mRNA (2.6+/-0.8-fold) in the left ventricular myocardium, which was not attendant with an alteration of ETA-R, ECE and ppET-1 mRNA expression. (3) An upregulation of the relative expression level of ETB-R protein due to ovariectomy was also demonstrated by radioligand binding assay. (4) Upregulation of both ETB-R mRNA and ETB-R protein expression was completely inhibited by E2 replacement. (5) To confirm these results in in vitro experiments, we quantified the mRNA of ET-R subtypes from isolated cardiomyocytes in the presence and absence of E2 (10-8 m, 24 h). Our data showed a markedly downregulated level of ETB-R mRNA in cardiomyocytes stimulated with E2. ETB-R downregulation was not attendant with the alteration of ETA-R, ECE and ppET-1 mRNA expression. (6) Taken together, these data demonstrate that estrogen regulates the expression of ETB-R in rat ventricular myocardium in vivo and in vitro. These observations may help to understand gender-based differences found in cardiovascular disease.

The Cardiac Cocaine Connection

Cardiovascular Research. Oct, 2003  |  Pubmed ID: 14553818

Sex-specific Differences in Ventricular Expression and Function of Parathyroid Hormone-related Peptide

Cardiovascular Research. Feb, 2004  |  Pubmed ID: 14736547

Parathyroid hormone-related peptide (PTHrP) expression is modulated by estrogen. It is expressed in coronary endothelial cells and involved in the endothelium-dependent regulation of coronary resistance and cardiac function. In the present study, we hypothesized that endogenously synthesized and released PTHrP contributes to sex-specific differences in the regulation of cardiac function.

Female Mice Lacking Estrogen Receptor Beta Display Prolonged Ventricular Repolarization and Reduced Ventricular Automaticity After Myocardial Infarction

Circulation. May, 2005  |  Pubmed ID: 15867180

Major gender-based differences in the incidence of ventricular tachyarrhythmia after myocardial infarction have been shown in humans. Although the underlying mechanisms are unclear, earlier studies suggest that estrogen receptor-mediated effects play a major role in this process.

The Influence of Oestrogen-deficiency and ACE Inhibition on the Progression of Myocardial Hypertrophy in Spontaneously Hypertensive Rats

European Journal of Heart Failure. Dec, 2005  |  Pubmed ID: 15922661

ACE inhibitors are widely used to antagonize the biological activity of angiotensin II in hypertensive heart disease. Oestrogen reduces angiotensin type 1 receptor expression, and thereby modifies angiotensin signalling.

Toll-like Receptor 4, Nitric Oxide, and Myocardial Depression in Endotoxemia

Shock (Augusta, Ga.). Jan, 2006  |  Pubmed ID: 16369185

The molecular mechanisms that mediate gram-negative sepsis-associated myocardial dysfunction remain elusive. Myocardial expression of inflammatory mediators is Toll-like receptor 4 (TLR4) dependent. However, it remains to be elucidated whether TLR4, expressed on cardiac myocytes, mediates impairment of cardiac contractility after lipopolysaccharide (LPS) application. Cardiac myocyte contractility, measured as sarcomere shortening of isolated cardiac myocytes from C3H/HeJ (with nonfunctional TLR4) and C3H/HeN (control), were recorded at stimulation frequencies between 0.5 and 10 Hz and after incubation with 1 and 10 mug/mL LPS for up to 8 h. Control cells treated with LPS were investigated with and without a competitive LPS inhibitor (E5564) and a specific inducible nitric oxide synthase (iNOS) inhibitor S-methylisothiourea. In control mice, LPS reduced sarcomere shortening amplitude and prolonged duration of relaxation, whereas sarcomere shortening of C3H/HeJ cells was insensitive to LPS. NFkappaB and iNOS were upregulated after LPS application in control mice compared with C3H/HeJ. Inhibition of TLR4 by E5564 as well as inhibition of iNOS prevented the influence of LPS on contractile activity in control myocytes. LPS-dependent suppression of cardiac myocyte contractility was significantly blunted in C3H/HeJ mice. Competitive inhibition of functional TLR4 with E5564 protects cardiac myocyte contractility against LPS. These findings suggest that TLR4, expressed on cardiac myocytes, contributes to sepsis-induced myocardial dysfunction. E5564, currently under investigation in two clinical phase II trials, seems to be a new therapeutic option for the treatment of myocardial dysfunction in sepsis associated with endotoxemia.

Estrogen Receptor Beta Protects the Murine Heart Against Left Ventricular Hypertrophy

Arteriosclerosis, Thrombosis, and Vascular Biology. Jul, 2006  |  Pubmed ID: 16627800

Left ventricular hypertrophy (LVH) displays significant gender-based differences. 17beta-estradiol (E2) plays an important role in this process because it can attenuate pressure overload hypertrophy via 2 distinct estrogen receptors (ERs): ERalpha and ERbeta. However, which ER is critically involved in the modulation of LVH is poorly understood. We therefore used ERalpha-deficient (ERalpha-/-) and ERbeta-deficient (ERbeta-/-) mice to analyze the respective ER-mediated effects.

Myocardial Injury Modulates the Innate Immune System and Changes Myocardial Sensitivity

Basic Research in Cardiology. Sep, 2006  |  Pubmed ID: 16699746

Transverse aortic constriction (TAC) results in a transient increase of proinflammatory cytokines, which return to baseline levels within 3 d. In contrast to cytokine baseline levels, the myocardium remains capable to respond even stronger to a new stimulus. As the molecular mechanisms for this phenomenon are unknown, we tested whether TAC modulates the innate immune system in mice and changes the inflammatory reaction to a new stimulus.

Bone Loss After Total Hip Arthroplasty

Rheumatology International. Jul, 2006  |  Pubmed ID: 16763871

The aim of the present study is to evaluate periprosthetic bone loss and to compare it with the bone loss in other areas of the body. We also aim to shed light on the course of bone mineral density (BMD) in patients with cemented femoral prosthesis in comparison with those with uncemented ones. We analyzed the BMD using dual-energy X-ray absorptiometry (DEXA) in a consecutively recruited convenience sample of 50 patients with cemented and uncemented total hip arthroplasty (THA). BMD was measured within the first month after surgery as well as 1 year later. In ten of the patients (20%) previously undiagnosed osteoporosis was revealed. Osteoporosis was significantly more frequently detected in patients with cemented compared to those with uncemented femoral stem. We found a significant loss in BMD in the periprosthetic femoral region compared with no losses in other body regions (lumbar spine, radius, contralateral hip). The magnitude of this loss was the highest in Gruen-Zone 7 (mean 15.2% per year). We found no BMD loss difference between patients with cemented and uncemented prosthesis in the Gruen-Zone 2-7. In conclusion these periprosthetic losses may be due to local factors such as periprosthetic bone remodeling, as they contrast with the course of BMD in the lumbar spine, radius and not operated hip.

Toll-like Receptor 4 Modulates Myocardial Ischaemia-reperfusion Injury: Role of Matrix Metalloproteinases

European Journal of Heart Failure. Nov, 2006  |  Pubmed ID: 16829192

Toll-like receptor 4 (TLR4) mediates innate immune responses following endotoxemia and myocardial ischaemia-reperfusion (I/R) injury. Pre-treatment with the major TLR4 ligand lipopolysaccharide (LPS) reduces infarct size. Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) play a crucial role in endotoxemia possibly also determining I/R injury.

Toll-like Receptor 4 Deficiency: Smaller Infarcts, but No Gain in Function

BMC Physiology. 2007  |  Pubmed ID: 17592640

It has been reported that Toll-like receptor 4 (TLR4) deficiency reduces infarct size after myocardial ischemia/reperfusion (MI/R). However, measurement of MI/R injury was limited and did not include cardiac function. In a chronic closed-chest model we assessed whether cardiac function is preserved in TLR4-deficient mice (C3H/HeJ) following MI/R, and whether myocardial and systemic cytokine expression differed compared to wild type (WT).

Enhanced Heterogeneity of Myocardial Conduction and Severe Cardiac Electrical Instability in Annexin A7-deficient Mice

Cardiovascular Research. Nov, 2007  |  Pubmed ID: 17662970

Annexin A7 is involved in cardiomyocyte membrane organization and Ca(2+)-dependent signalling processes. We investigated the impact of annexin A7 on cardiac electrophysiological properties using an annexin A7-deficient mouse strain (annexin A7(-/-)).

CpG Oligonucleotide Activates Toll-like Receptor 9 and Causes Lung Inflammation in Vivo

Respiratory Research. 2007  |  Pubmed ID: 17925007

Bacterial DNA containing motifs of unmethylated CpG dinucleotides (CpG-ODN) initiate an innate immune response mediated by the pattern recognition receptor Toll-like receptor 9 (TLR9). This leads in particular to the expression of proinflammatory mediators such as tumor necrosis factor (TNF-alpha) and interleukin-1beta (IL-1beta). TLR9 is expressed in human and murine pulmonary tissue and induction of proinflammatory mediators has been linked to the development of acute lung injury. Therefore, the hypothesis was tested whether CpG-ODN administration induces an inflammatory response in the lung via TLR9 in vivo.

Parathyroid Hormone-related Protein (PTHrP) Signal Cascade Modulates Myocardial Dysfunction in the Pressure Overloaded Heart

European Journal of Heart Failure. Dec, 2007  |  Pubmed ID: 17997355

Pressure overload induces the cardiac expression of parathyroid hormone-related protein (PTHrP). Plasma levels are elevated in patients with heart disease. It is unknown whether this represents an epiphenomenon or suggests involvement in hypertrophy.

Age and Hypertrophy Related Changes in Contractile Post-rest Behavior and Action Potential Properties in Isolated Rat Myocytes

Age (Dordrecht, Netherlands). Dec, 2007  |  Pubmed ID: 19424839

"Physiological" aging as well as early and progressive cardiac hypertrophy may affect action potential (AP) pattern, contractile function, and Ca(2+) handling. We hypothesize that contractile function is disturbed in hypertrophy from early stages and is differently affected in aged myocardium. In vivo function, cardiomyocyte contractile behavior and APs were compared in Wistar-Kyoto (WIS) rats and spontaneously hypertensive rats (SHR) at different ages and degrees of hypertrophy (3-4, 9-11, 20-24 months). Post-rest (PR) behavior was used to investigate the relative contribution of the sarcoplasmic reticulum (SR) and the Na/Ca exchanger (NCX) to cytosolic Ca(2+) removal. APs were recorded by whole-cell current-clamp and sarcomere shortening by video microscopy. Cyclopiazonic acid was used to suppress Ca(2+) ATPase (SERCA) function. Heart weight/body weight ratio was increased in SHR versus WIS within all age groups. Myocyte steady state (SS) shortening amplitude was reduced in young SHR versus WIS. Aging led to a significant decay of SS contractile amplitude and relengthening velocity in WIS, but the PR potentiation was maintained. In contrast, aging in SHR led to a decrease of PR potentiation, while SS contraction and relengthening velocity increased. APD(50%) was always prolonged in SHR versus WIS. With aging, APD(50%) increased in both WIS and SHR, but was still shorter in WIS. However, in old WIS the late AP portion (APD(90%)) was prolonged. Ca(2+) handling and AP properties are disturbed progressively with aging and with increasing hypertrophy. Decreased amplitude of shortening and velocity of relengthening in aged WIS may be attributed to reduced SERCA function. In SHR, an increase in SR leak and shift towards transmembraneous Ca handling via NCX may be responsible for the changes in contractile function. A prolonged APD(90%) in aged WIS may be an adaptive mechanism to preserve basal contractility. Therefore, the effects on contractile parameters and AP are different in hypertrophy and aging.

Bacterial DNA Induces Myocardial Inflammation and Reduces Cardiomyocyte Contractility: Role of Toll-like Receptor 9

Cardiovascular Research. Apr, 2008  |  Pubmed ID: 18194990

Myocardial function is severely compromised during sepsis. Several underlying mechanisms have been proposed. The innate immune system, i.e. toll-like receptor (TLR) 2 and 4, significantly contributes to cardiac dysfunction. Little is known regarding TLR9 and its pathogenic ligand bacterial DNA in the myocardium. We therefore studied the role of TLR9 in myocardial inflammation and cardiac contractility.

Absence of 2-hydroxylated Sphingolipids is Compatible with Normal Neural Development but Causes Late-onset Axon and Myelin Sheath Degeneration

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Sep, 2008  |  Pubmed ID: 18815260

Sphingolipids containing 2-hydroxylated fatty acids are among the most abundant lipid components of the myelin sheath and therefore are thought to play an important role in formation and function of myelin. To prove this hypothesis, we generated mice lacking a functional fatty acid 2-hydroxylase (FA2H) gene. FA2H-deficient (FA2H(-/-)) mice lacked 2-hydroxylated sphingolipids in the brain and in peripheral nerves. In contrast, nonhydroxylated galactosylceramide was increased in FA2H(-/-) mice. However, oligodendrocyte differentiation examined by in situ hybridization with cRNA probes for proteolipid protein and PDGFalpha receptor and the time course of myelin formation were not altered in FA2H(-/-) mice compared with wild-type littermates. Nerve conduction velocity measurements of sciatic nerves revealed no significant differences between FA2H(-/-) and wild-type mice. Moreover, myelin of FA2H(-/-) mice up to 5 months of age appeared normal at the ultrastructural level, in the CNS and peripheral nervous system. Myelin thickness and g-ratios were normal in FA2H(-/-) mice. Aged (18-month-old) FA2H(-/-) mice, however, exhibited scattered axonal and myelin sheath degeneration in the spinal cord and an even more pronounced loss of stainability of myelin sheaths in sciatic nerves. These results show that structurally and functionally normal myelin can be formed in the absence of 2-hydroxylated sphingolipids but that its long-term maintenance is strikingly impaired. Because axon degeneration appear to start rather early with respect to myelin degenerations, these lipids might be required for glial support of axon function.

Cell-specific Effects of Nitric Oxide Deficiency on Parathyroid Hormone-related Peptide (PTHrP) Responsiveness and PTH1 Receptor Expression in Cardiovascular Cells

Endocrinology. Aug, 2009  |  Pubmed ID: 19342458

The missing influence of estrogen on endothelial nitric oxide (NO) synthase often forms the basis for a worsening of the cardiac risk profile for women in postmenopause. Various studies have shown that decreasing estrogen levels also directly effect the expression of PTHrP and TGFbeta1. PTHrP is involved in the endothelium-dependent regulation of coronary resistance and cardiac function. The current study investigates to what extent chronic NO deficit affects the cardiac effects of PTHrP. NO deficit was achieved in female adult rats by feeding them the NO synthase inhibitor N-omega-nitro-L-arginine methyl ester over a period of 4 wk. Isolated hearts of the conditioned animals were investigated in Langendorff technique and perfused for 3 min with 100 nM PTHrP. The contraction behavior of isolated cardiomyocytes was registered in a cell-edge detection system. Hearts from untreated animals displayed a significant drop in left ventricular developed pressure and a pronounced increase in heart rate in consequence of short term PTHrP stimulation. In hearts from NO-deficient rats PTHrP no longer affected the inotropy and chronotropy. The vasodilating effect of PTHrP on coronary vessels was, however, independent of the NO level. These changes were accompanied by a differing expression of the PTH1 receptor. TGFbeta1 was identified as an important mediator for the regulation of the PTH1 receptor in myocytic but not endothelial cells. These results indicate that chronic NO deficit down-regulates the PTH1 receptor in a TGFbeta1-dependent way. These findings are important with respect to the relatively new therapy of postmenopausal osteoporosis with PTHrP analogs.

Lack of Gelsolin Promotes Perpetuation of Atrial Fibrillation in the Mouse Heart

Journal of Interventional Cardiac Electrophysiology : an International Journal of Arrhythmias and Pacing. Oct, 2009  |  Pubmed ID: 19669398

Gelsolin (gsn) is involved in the reorganization of the cytoskeleton, thereby modulating cardiomyocytal L-type Ca(2+) channels. We investigated global cardiac electrophysiological characteristics in a gsn-deficient (gsn(-/-)) mouse strain.

Complete Loss of Murine Xin Results in a Mild Cardiac Phenotype with Altered Distribution of Intercalated Discs

Cardiovascular Research. Mar, 2010  |  Pubmed ID: 19843512

Xin is a striated muscle-specific F-actin binding protein that has been implicated in cardiomyopathies. In cardiomyocytes, Xin is localized at intercalated discs (IDs). Mice lacking only two of the three Xin isoforms (XinAB(-/-) mice) develop severe cardiac hypertrophy. To further investigate the function of Xin variants in the mammalian heart, we generated XinABC(-/-) mice deficient in all Xin isoforms.

The Toll-like Receptor 4-antagonist Eritoran Reduces Murine Cardiac Hypertrophy

European Journal of Heart Failure. Jun, 2011  |  Pubmed ID: 21613426

Toll-like receptor 4 (TLR4) recognizes lipopolysaccharides and endogenous ligands released after organ injury. Deficiency of TLR4 attenuates the development of left ventricular hypertrophy after transverse aortic constriction (TAC) in mice. We hypothesized that application of the TLR4 antagonist eritoran may also reduce cardiac hypertrophy after TAC surgery.

In Vivo Toll-like Receptor 4 Antagonism Restores Cardiac Function During Endotoxemia

Shock (Augusta, Ga.). Dec, 2011  |  Pubmed ID: 22089127

Severe sepsis and septic shock are often accompanied by acute cardiovascular depression. Lipopolysaccharide (LPS) signaling via Toll-like receptor 4 (TLR4) can induce septic organ dysfunction. The aim of this study was to elucidate the in vivo impact of pharmacological TLR4 antagonism on LPS-induced cardiovascular depression using eritoran tetrasodium (E5564). To simulate sepsis, C3H/HeN mice were challenged i.p. with 2 mg/kg body weight LPS. With the intent to antagonize the LPS effects, eritoran was administered i.v. (4 mg/kg body weight). Physical activity, peripheral blood pressure, and heart frequency were recorded before and after LPS and eritoran injection. In addition, intracardiac hemodynamic parameters were analyzed with a pressure conductance catheter. After 2 and 6 h of LPS stimulation ± eritoran treatment, the hearts and aortae were harvested, and TLR as well as inflammatory mediator expression was measured using reverse transcription-quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Lipopolysaccharide significantly decreased arterial blood pressure over time. Administration of eritoran partially prevented the LPS-dependent reduction in blood pressure and preserved cardiac function. In addition, LPS increased the expression of CD14 and TLR2 in cardiac and aortic tissue. In aortic tissue, eritoran attenuated this increase, whereas no significant reduction was observed in the heart. Furthermore, cardiac and aortic inducible nitric oxide synthetase mRNA levels were significantly increased 6 h after LPS application. This effect was reduced in the presence of eritoran. In summary, the beneficial influence of eritoran on cardiovascular function in vivo seems to rely mainly on reduction of LPS-induced inducible nitric oxide synthetase expression as well as on attenuated cytokine expression in the vascular wall.

Interactions of Adiponectin and Lipopolysaccharide from Porphyromonas Gingivalis on Human Oral Epithelial Cells

PloS One. 2012  |  Pubmed ID: 22319581

Periodontitis is an inflammatory disease caused by pathogenic microorganisms, such as Porphyromonas gingivalis, and characterized by the destruction of the periodontium. Obese individuals have an increased risk for periodontitis and show decreased serum levels of adiponectin. This in-vitro study was established to examine whether adiponectin modulates critical effects of lipopolysaccharide (LPS) from P. gingivalis on oral epithelial cells (OECs).

Effect of Intermittent PTH(1-34) on Human Periodontal Ligament Cells Transplanted into Immunocompromised Mice

Tissue Engineering. Part A. May, 2012  |  Pubmed ID: 22497226

Residual periodontal ligament (PDL) cells in the damaged tissue are considered a prerequisite for a successful regeneration of the periodontal architecture with all its components, including gingiva, PDL, cementum, and bone. Among other approaches, current concepts in tissue engineering aim at a hormonal support of the regenerative capacity of PDL cells as well as at a supplementation of lost cells for regeneration. Here, we investigated how far an anabolic, intermittent parathyroid hormone (iPTH) administration would enhance the osteoblastic differentiation of PDL cells and the cellular ability to mineralize the extracellular matrix in an in vivo transplantation model. PDL cells were predifferentiated in a standard osteogenic medium for 3 weeks before subcutaneous transplantation into CD-1 nude mice using gelatin sponges as carrier. Daily injections of 40 μg/kg body weight PTH(1-34) or an equivalent dose of vehicle for 4 weeks were followed by explantation of the specimens and an immunohistochemical analysis of the osteoblastic marker proteins alkaline phosphatase (ALP), osteopontin, and osteocalcin. Signs of biomineralization were visualized by means of alizarin red staining. For verification of the systemic effect of iPTH application, blood serum levels of osteocalcin were determined. The osteogenic medium stimulated the expression of ALP and PTH1-receptor mRNA in the cultures. After transplantation, iPTH resulted in an increased cytoplasmic and extracellular immunoreactivity for all markers investigated. In contrast to only sporadic areas of mineralization under control conditions, several foci of mineralization were observed in the iPTH group. Blood serum levels of osteocalcin were elevated significantly with iPTH. These data indicate that the osteoblastic differentiation of human PDL cells and their ability for biomineralization can be positively influenced by iPTH in vivo. These findings hold out a promising prospect for the support of periodontal regeneration.

Vascular Dysfunction Following Polymicrobial Sepsis: Role of Pattern Recognition Receptors

PloS One. 2012  |  Pubmed ID: 22970242

Aim was to elucidate the specific role of pattern recognition receptors in vascular dysfunction during polymicrobial sepsis (colon ascendens stent peritonitis, CASP).

Priming with Synthetic Oligonucleotides Attenuates Pressure Overload-induced Inflammation and Cardiac Hypertrophy in Mice

Cardiovascular Research. Dec, 2012  |  Pubmed ID: 22977006

Inflammation and Toll-like receptor (TLR) signalling have been linked to the development of cardiac hypertrophy following transverse aortic constriction (TAC). In the present study, we investigated whether pre-treatment with the synthetic TLR9 ligands 1668-thioate or 1612-thioate modulates the progression of TAC-induced cardiac inflammation and hypertrophy.

Bisphenol A Inhibits Voltage-activated Ca(2+) Channels in Vitro: Mechanisms and Structural Requirements

Molecular Pharmacology. Feb, 2013  |  Pubmed ID: 23197648

Bisphenol A (BPA), a high volume production chemical compound attracts growing attention as a health-relevant xenobiotic in humans. It can directly bind to hormone receptors, enzymes, and ion channels to become biologically active. In this study we show that BPA acts as a potent blocker of voltage-activated Ca(2+) channels. We determined the mechanisms of block and the structural elements of BPA essential for its action. Macroscopic Ba(2+) / Ca(2+) currents through native L-, N-, P/Q-, T-type Ca(2+) channels in rat endocrine GH(3) cells, mouse dorsal root ganglion neurons or cardiac myocytes, and recombinant human R-type Ca(2+) channels expressed in human embryonic kidney (HEK) 293 cells were rapidly and reversibly inhibited by BPA with similar potency (EC(50) values: 26-35 μM). Pharmacological and biophysical analysis of R-type Ca(2+) channels revealed that BPA interacts with the extracellular part of the channel protein. Its action does not require intracellular signaling pathways, is neither voltage- nor use-dependent, and does not affect channel gating. This indicates that BPA interacts with the channel in its resting state by directly binding to an external site outside the pore-forming region. Structure-effect analyses of various phenolic and bisphenolic compounds revealed that 1) a double-alkylated (R-C(CH(3))(2)-R, R-C(CH(3))(CH(2)CH(3))-R), or double-trifluoromethylated sp(3)-hybridized carbon atom between the two aromatic rings and 2) the two aromatic moieties in angulated orientation are optimal for BPA's effectiveness. Since BPA highly pollutes the environment and is incorporated into the human organism, our data may provide a basis for future studies relevant for human health and development.

Toll-like Receptor 9 Promotes Cardiac Inflammation and Heart Failure During Polymicrobial Sepsis

Mediators of Inflammation. 2013  |  Pubmed ID: 23935245

Aim was to elucidate the role of toll-like receptor 9 (TLR9) in cardiac inflammation and septic heart failure in a murine model of polymicrobial sepsis.

TLR2 Stimulation Induces Cardiac Inflammation but Not Cardiac Depression in Vivo

Journal of Inflammation (London, England). Oct, 2013  |  Pubmed ID: 24171786

Bacteria such as Staphylococcus aureus induce myocardial dysfunction in vivo. To rectify conflicting evidence about the role of TLR2 signaling and cardiac dysfunction, we hypothesized that the specific TLR2 agonist purified lipoteichoic acid (LTA) from S. aureus contributes to cardiac dysfunction in vitro and in vivo.

Antibiotics Regulate the Immune Response in Both Presence and Absence of Lipopolysaccharide Through Modulation of Toll-like Receptors, Cytokine Production and Phagocytosis in Vitro

International Immunopharmacology. Jan, 2014  |  Pubmed ID: 24239744

The inflammatory response to pathogen-associated molecular patterns such as lipopolysaccharide (LPS) in sepsis is mediated via Toll-like receptors (TLRs). Since TLRs also trigger various immune functions, including phagocytosis, their modulation is a promising strategy in the treatment of sepsis. As antibiotics have immunomodulatory properties, this study examined the effect of commonly used classes of antibiotics on i) the expression of TLRs and cytokines and ii) the phagocytic activity under sepsis-like conditions in vitro. This was achieved by incubating THP-1 monocytes and peripheral blood mononuclear cells (PBMCs) obtained from patients after open-heart surgery with the addition of LPS and six key antibiotics (piperacillin, doxycycline, erythromycin, moxifloxacin or gentamicin). After 24h, mRNA levels of both cytokines (IL-1β, IL-6) and TLRs (1, 2, 4, and 6) were monitored and phagocytosis was determined following coincubation with Escherichia coli. Each antibiotic differentially regulated the gene expression of the investigated TLRs and cytokines in monocytes. Erythromycin, moxifloxacin and doxycyclin displayed the strongest effects and changed mRNA-levels of the investigated genes up to 5.6-fold. Consistent with this, antibiotics and, in particular, moxifloxacin, regulated the TLR-and cytokine expression in activated PBMCs obtained from patients after open-heart surgery. Furthermore, piperacillin, doxycyclin and moxifloxacin inhibited the phagocytic activity of monocytes. Our results suggest that antibiotics regulate the immune response by modulating TLR- and cytokine expression as well as phagocytosis under septic conditions. Moxifloxacin, doxycycline and erythromycin were shown to possess the strongest immunomodulatory effects and these antibiotic classes should be considered for future immunomodulatory studies in sepsis.

Ly6C(low) and Not Ly6C(high) Macrophages Accumulate First in the Heart in a Model of Murine Pressure-overload

PloS One. 2014  |  Pubmed ID: 25415601

Cardiac tissue remodeling in the course of chronic left ventricular hypertrophy requires phagocytes which degrade cellular debris, initiate and maintain tissue inflammation and reorganization. The dynamics of phagocytes in left ventricular hypertrophy have not been systematically studied. Here, we characterized the temporal accumulation of leukocytes in the cardiac immune response by flow cytometry and fluorescence microscopy at day 3, 6 and 21 following transverse aortic constriction (TAC). Cardiac hypertrophy due to chronic pressure overload causes cardiac immune response and inflammation represented by an increase of immune cells at all three time points among which neutrophils reached their maximum at day 3 and macrophages at day 6. The cardiac macrophage population consisted of both Ly6C(low) and Ly6C(high) macrophages. Ly6C(low) macrophages were more abundant peaking at day 6 in response to pressure overload. During the development of cardiac hypertrophy the expression pattern of adhesion molecules was investigated by qRT-PCR and flow cytometry. CD11b, CX3CR1 and ICAM-1 determined by qRT-PCR in whole cardiac tissue were up-regulated in response to pressure overload at day 3 and 6. CD11b and CX3CR1 were significantly increased by TAC on the surface of Ly6C(low) but not on Ly6C(high) macrophages. Furthermore, ICAM-1 was up-regulated on cardiac endothelial cells. In fluorescence microscopy Ly6C(low) macrophages could be observed attached to the intra- and extra-vascular vessel-wall. Taken together, TAC induced the expression of adhesion molecules, which may explain the accumulation of Ly6C(low) macrophages in the cardiac tissue, where these cells might contribute to cardiac inflammation and remodeling in response to pressure overload.

Postconditioning with a CpG Containing Oligodeoxynucleotide Ameliorates Myocardial Infarction in a Murine Closed-chest Model

Life Sciences. Oct, 2014  |  Pubmed ID: 25445440

Toll-like receptor (TLR)9 ligand CpG-oligodeoxynucleotide (CpG-ODN) exerts preconditioning in myocardial ischemia/reperfusion. We hypothesized a postconditioning effect of CpG-ODN in a murine closed-chest model of myocardial infarction.

The Toxic Effect of R350P Mutant Desmin in Striated Muscle of Man and Mouse

Acta Neuropathologica. Feb, 2015  |  Pubmed ID: 25394388

Mutations of the human desmin gene on chromosome 2q35 cause autosomal dominant, autosomal recessive and sporadic forms of protein aggregation myopathies and cardiomyopathies. We generated R349P desmin knock-in mice, which harbor the ortholog of the most frequently occurring human desmin missense mutation R350P. These mice develop age-dependent desmin-positive protein aggregation pathology, skeletal muscle weakness, dilated cardiomyopathy, as well as cardiac arrhythmias and conduction defects. For the first time, we report the expression level and subcellular distribution of mutant versus wild-type desmin in our mouse model as well as in skeletal muscle specimens derived from human R350P desminopathies. Furthermore, we demonstrate that the missense-mutant desmin inflicts changes of the subcellular localization and turnover of desmin itself and of direct desmin-binding partners. Our findings unveil a novel principle of pathogenesis, in which not the presence of protein aggregates, but disruption of the extrasarcomeric intermediate filament network leads to increased mechanical vulnerability of muscle fibers. These structural defects elicited at the myofiber level finally impact the entire organ and subsequently cause myopathy and cardiomyopathy.

Evaluation of Near-infrared Spectroscopy Under Apnea-dependent Hypoxia in Humans

Journal of Clinical Monitoring and Computing. Dec, 2015  |  Pubmed ID: 25649718

In this study we investigated the responsiveness of near-infrared spectroscopy (NIRS) recordings measuring regional cerebral tissue oxygenation (rSO2) during hypoxia in apneic divers. The goal was to mimic dynamic hypoxia as present during cardiopulmonary resuscitation, laryngospasm, airway obstruction, or the "cannot ventilate cannot intubate" situation. Ten experienced apneic divers performed maximal breath hold maneuvers under dry conditions. SpO2 was measured by Masimo™ pulse oximetry on the forefinger of the left hand. NIRS was measured by NONIN Medical's EQUANOX™ on the forehead or above the musculus quadriceps femoris. Following apnea median cerebral rSO2 and SpO2 values decreased significantly from 71 to 54 and from 100 to 65%, respectively. As soon as cerebral rSO2 and SpO2 values decreased monotonically the correlation between normalized cerebral rSO2 and SpO2 values was highly significant (Pearson correlation coefficient = 0.893). Prior to correlation analyses, the values were normalized by dividing them by the individual means of stable pre-apneic measurements. Cerebral rSO2 measured re-saturation after termination of apnea significantly earlier (10 s, SD = 3.6 s) compared to SpO2 monitoring (21 s, SD = 4.4 s) [t(9) = 7.703, p < 0.001, r(2) = 0.868]. Our data demonstrate that NIRS monitoring reliably measures dynamic changes in cerebral tissue oxygen saturation, and identifies successful re-saturation faster than SpO2. Measuring cerebral rSO2 may prove beneficial in case of respiratory emergencies and during pulseless situations where SpO2 monitoring is impossible.

Linezolid, Vancomycin and Daptomycin Modulate Cytokine Production, Toll-like Receptors and Phagocytosis in a Human in Vitro Model of Sepsis

The Journal of Antibiotics. Aug, 2015  |  Pubmed ID: 25735844

Conventional antibiotics exhibit immunomodulatory properties beneficial in the treatment of sepsis. Antibiotic-resistant Gram-positive bacteria have become a problem in sepsis therapy, giving rise to increased use of last-resort antibiotics; for example, linezolid (LIN), vancomycin (VAN) and daptomycin (DAP). As the immunomodulatory properties of these antibiotics in treating sepsis are unknown, this study examined the effect of VAN, LIN and DAP on the immune response under sepsis-like conditions in vitro. Lipopolysaccharide (LPS)-activated THP-1 monocytes were incubated with LIN, VAN or DAP. Gene expression of cytokines (TNFα, IL-1β, IL-6, IL-10) and Toll-like receptors (TLR1, 2, 4, 6, 7 and 9) was monitored and phagocytosis was determined following coincubation with E. coli. The antibiotics differentially modulated the gene expression of the investigated cytokines. While LIN and VAN upregulated the expression of all TLRs, DAP downregulated mRNA levels of TLR1, TLR2 and TLR6, which recognize pathogen-associated molecular patterns from Gram-positive bacteria. In addition, LIN inhibited, whereas VAN promoted the phagocytic activity of monocytes. Our results suggest that LIN and VAN possess pro-inflammatory properties, whereas DAP might reduce the immune response to Gram-positive bacteria in sepsis. Furthermore, VAN might be beneficial in the prevention of Gram-negative infections by increasing the phagocytosis of E. coli.

Antifungal Antibiotics Modulate the Pro-inflammatory Cytokine Production and Phagocytic Activity of Human Monocytes in an in Vitro Sepsis Model

Life Sciences. Nov, 2015  |  Pubmed ID: 26382596

The incidence of secondary systemic fungal infections has sharply increased in bacterial septic patients. Antimycotics exhibit immunomodulatory properties, yet these effects are incompletely understood in secondary systemic fungal infections following bacterial sepsis. We investigated a model of systemic inflammation to determine whether antimycotics (liposomal amphotericin B (L-AMB), itraconazol (ITC), and anidulafungin (ANI)) modulate the gene and protein expression as well as the phagocytic activity of lipopolysaccharide (LPS)-stimulated human monocytes.

Tlr4 Deficiency Protects Against Cardiac Pressure Overload Induced Hyperinflammation

PloS One. 2015  |  Pubmed ID: 26588247

Transverse aortic constriction provokes a pro-inflammatory reaction and results in cardiac hypertrophy. Endogenous ligands contribute to cardiac hypertrophy via toll-like receptor (TLR)-4 binding. A lack of TLR4 signaling diminishes hypertrophy and inflammation. Wild type mice undergoing aortic constriction respond to a lipopolysaccharide second-hit stimulus with hyperinflammation. The objective of this study was to assess whether other second-hit challenges utilizing TLR ligands provoke a comparable inflammatory reaction, and to find out whether this response is absent in TLR4 deficient mice. Assuming that cardiac stress alters the expression of pattern recognition receptors we analyzed the effects of transverse aortic constriction and second-hit virulence factor treatment on TLR expression, as well as cytokine regulation. Wild type and Tlr4-/- mice were subjected to three days of TAC and subsequently confronted with gram-positive TLR2 ligand lipoteichoic acid (LTA, 15 mg/g bodyweight) or synthetic CpG-oligodesoxynucleotide 1668 thioate (20 nmol/kg bodyweight, 30 min after D-galactosamin desensitization) signaling via TLR9. Hemodynamic measurements and organ preservation were performed 6 h after stimulation. Indeed, the study revealed a robust enhancement of LTA induced pattern recognition receptor and cytokine mRNA expression and a LTA-dependent reduction of hemodynamic pressure in TAC wild type mice. Second-Hit treatment with CpG-ODNs led to similar results. However, second-hit effects were abolished in Tlr4-/- mice. In total, these data indicate for the first time that cardiac stress increases the inflammatory response towards both, gram-negative and gram-positive, TLR ligands as well as bacterial DNA. The decrease of the inflammatory response upon TLR2 and -9 ligand challenge in TAC Tlr4-/- mice demonstrates that a lack of TLR4 signaling does not only prevent left ventricular hypertrophy but also protects the mice from a cardiac stress induced hyperinflammatory reaction.

Ghrelin Promotes Oral Tumor Cell Proliferation by Modifying GLUT1 Expression

Cellular and Molecular Life Sciences : CMLS. Mar, 2016  |  Pubmed ID: 26407611

In our study, ghrelin was investigated with respect to its capacity on proliferative effects and molecular correlations on oral tumor cells. The presence of all molecular components of the ghrelin system, i.e., ghrelin and its receptors, was analyzed and could be detected using real-time PCR and immunohistochemistry. To examine cellular effects caused by ghrelin and to clarify downstream-regulatory mechanisms, two different oral tumor cell lines (BHY and HN) were used in cell culture experiments. Stimulation of either cell line with ghrelin led to a significantly increased proliferation. Signal transduction occurred through phosphorylation of GSK-3β and nuclear translocation of β-catenin. This effect could be inhibited by blocking protein kinase A. Glucose transporter1 (GLUT1), as an important factor for delivering sufficient amounts of glucose to tumor cells having high requirements for this carbohydrate (Warburg effect) was up-regulated by exogenous and endogenous ghrelin. Silencing intracellular ghrelin concentrations using siRNA led to a significant decreased expression of GLUT1 and proliferation. In conclusion, our study describes the role for the appetite-stimulating peptide hormone ghrelin in oral cancer proliferation under the particular aspect of glucose uptake: (1) tumor cells are a source of ghrelin. (2) Ghrelin affects tumor cell proliferation through autocrine and/or paracrine activity. (3) Ghrelin modulates GLUT1 expression and thus indirectly enhances tumor cell proliferation. These findings are of major relevance, because glucose uptake is assumed to be a promising target for cancer treatment.

Loss of the LIM-only Protein Fhl2 Impairs Inflammatory Reaction and Scar Formation After Cardiac Ischemia Leading to Better Hemodynamic Performance

Life Sciences. Apr, 2016  |  Pubmed ID: 26921632

The pathogenesis of myocardial ischemia-reperfusion injury (MI/R) involves an inflammatory response. Since the four-and-a-half LIM domain-containing protein 2 (Fhl2) has been observed to modulate immune cell migration, we aimed to study the consequences of Fhl2(-/-) under MI/R with respect to immune reaction, scar formation, and hemodynamic performance.

Tlr2 Deficiency Does Not Limit the Development of Left Ventricular Hypertrophy in a Model of Transverse Aortic Constriction Induced Pressure Overload

Journal of Negative Results in Biomedicine. Apr, 2016  |  Pubmed ID: 27109115

Toll-like receptors (TLRs) are involved in a variety of cardiovascular disorders, including septic cardiomyopathy, ischemia/reperfusion, heart failure, and cardiac hypertrophy. Previous research revealed that TLR4 promotes cardiac hypertrophy in vivo. Therefore, we investigated whether TLR2 is also involved in the development of cardiac hypertrophy.

Sarcomeric Lesions and Remodeling Proximal to Intercalated Disks in Overload-induced Cardiac Hypertrophy

Experimental Cell Research. Oct, 2016  |  Pubmed ID: 27639425

Pressure overload induces cardiac remodeling involving both the contractile machinery and intercalated disks (IDs). Filamin C (FlnC) and Xin actin-binding repeat-containing proteins (XIRPs) are multi-adapters localizing in IDs of higher vertebrates. Knockout of the gene encoding Xin (Xirp1) in mice leads to a mild cardiac phenotype with ID mislocalization. In order to amplify this phenotype, we performed transverse aortic constriction (TAC) on control and Xirp1-deficient mice. TAC induced similar left ventricular hypertrophy in both genotypes, suggesting that the lack of Xin does not lead to higher susceptibility to cardiac overload. However, in both genotypes, FlnC appeared in "streaming" localizations across multiple sarcomeres proximal to the IDs, suggesting a remodeling response. Furthermore, FlnC-positive areas of remodeling, reminiscent of sarcomeric lesions previously described for skeletal muscles (but so far unreported in the heart), were also observed. These adaptations reflect a similarly strong effect of the pressure induced by TAC in both genotypes. However, 2 weeks post-operation TAC-treated knockout hearts had reduced levels of connexin43 and slightly increased incidents of ventricular tachycardia compared to their wild-type (WT) counterparts. Our findings highlight the FlnC-positive sarcomeric lesions and ID-proximal streaming as general remodeling responses in cardiac overload-induced hypertrophy.

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