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Biomedical subjects

Johannes-Peter Stasch

Publications and source records attributed to Johannes-Peter Stasch.

At least 19 recordsLinked to original sources
PubMed2006

Soluble guanylate cyclase stimulation on cardiovascular remodeling in angiotensin II-induced hypertensive rats.

It is unknown whether long-term pharmacological stimulation of soluble guanylate cyclase (sGC), elevating intracellular cGMP levels, has a beneficial effect on hypertension. The purpose of this study is to investigate the effects of BAY41-2272, an orally available sGC stimulator, on cardiovascular remodeling in hypertensive rats. Eight-week-old male Wistar rats with hypertension induced by angiotensin II infused subcutaneously at 250 ng/kg per minute were treated orally with a low ([L] 2 mg/kg per day) or high ([H] 10 mg/kg per day) dose of BAY41-2272 for 14 days. BAY41-2272-H partially suppressed the rise in blood pressure and reduced the heart weight (4.20+/-0.34 versus 3.68+/-0.20 mg/g; P<0.01), whereas BAY41-2272-L had no effect. However, both doses decreased the angiotensin II-induced left ventricular accumulation of collagen in the perivascular area (L, -20%, P<0.05; H, -30%, P<0.01) and myocardial interstitium (L, -21%, P<0.05; H, -38%, P<0.01), reducing the number of activated fibroblasts surrounding coronary arteries (L, -74%; H, -79%; P<0.05). BAY41-2272 downregulated the angiotensin II-induced left ventricular gene expression of type 1 collagen (L, -41%, P<0.05; H, -49%, P<0.01) and transforming growth factor-beta1 (L, -49%, P<0.05; H, -65%, P<0.01). cGMP levels were elevated by BAY41-2272 not only in the left ventricle, but also in cultured cardiac fibroblasts, resulting in reduced thymidine incorporation into the cells. Thus, stimulation of sGC by BAY41-2272 attenuates fibrosis of the left ventricle in rats with angiotensin II-induced hypertension partly in a pressure-independent manner, suggesting an important role for sGC generating cGMP in inhibiting cardiovascular remodeling.

Angiotensin II↗
PubMed2006

Identification of residues crucially involved in soluble guanylate cyclase activation.

The ubiquitous heterodimeric nitric oxide (NO) receptor soluble guanylate cyclase (sGC) plays a key role in various signal transduction pathways. Binding of NO takes place at the prosthetic heme moiety at the N-terminus of the beta(1)-subunit of sGC. The induced structural changes lead to an activation of the catalytic C-terminal domain of the enzyme and to an increased conversion of GTP into the second messenger cyclic GMP (cGMP). In the present work we selected and substituted different residues of the sGC heme-binding pocket based on a sGC homology model. The generated sGC variants were tested in a cGMP reporter cell for their effect on the enzyme activation by heme-dependent (NO, BAY 41-2272) stimulators and heme-independent (BAY 58-2667) activators. The use of these experimental tools allows the enzyme's heme content to be explored in a non-invasive manner. Asp(44), Asp(45) and Phe(74) of the beta(1)-subunit were identified as being crucially important for functional enzyme activation. beta(1)Asp(45) may serve as a switch between different conformational states of sGC and point to a possible mechanism of action of the heme dependent sGC stimulator BAY 41-2272. Furthermore, our data shows that the activation profile of beta(1)IIe(145) Tyr is unchanged compared to the native enzyme, suggesting that Tyr(145) does not confer the ability to distinguish between NO and O(2). In summary, the present work further elucidated intramolecular mechanisms underlying the NO- and BAY 41-2272-mediated sGC activation and raises questions regarding the postulated role of Tyr(145) for ligand discrimination.

Animals↗
PubMed2006

NO-independent activation of soluble guanylate cyclase prevents disease progression in rats with 5/6 nephrectomy.

1. Chronic renal disease is associated with oxidative stress, reduced nitric oxide (NO) availability and soluble guanylate cyclase (sGC) dysfunction. Recently, we discovered BAY 58-2667, a compound activating heme-deficient or oxidized sGC in a NO-independent manner. 2. We assessed potential of BAY 58-2667 in preventing cardiac and renal target organ damage in rats with 5/6 nephrectomy. 3. Male Wistar rats were allocated to three groups: 5/6 nephrectomy, 5/6 nephrectomy treated with BAY 58-2667 and sham operation. Study period was 18 weeks: blood pressure and creatinine clearance were assessed repeatedly. At study end blood samples were taken and hearts and kidneys harvested for histological studies. 4. BAY 58-2667 markedly lowered blood pressure in animals with 5/6 nephrectomy (untreated versus treated animals: 189+/-14 versus 146+/-11 mmHg, P<0.001). Left ventricular weight, cardiac myocyte diameter as well as cardiac arterial wall thickness significantly decreased in comparison to untreated animals with 5/6 nephrectomy. Natriuretic peptide plasma levels were also improved by BAY 58-2667. Kidney function and morphology as assessed by creatinine clearance, glomerulosclerosis, interstitial and perivascular fibrosis of intrarenal arteries were likewise significantly improved by BAY 58-2667. 5. This is the first study showing that BAY 58-2667 effectively lowers blood pressure, reduces left ventricular hypertrophy and slows renal disease progression in rats with 5/6 nephrectomy by targeting mainly oxidized sGC. Therefore, BAY 58-2667 represents a novel pharmacological principle with potential clinical value in treatment of chronic renal disease.

Albuminuria↗
PubMed2006

Diabetic endothelin B receptor-deficient rats develop severe hypertension and progressive renal failure.

The endothelin (ET) system has been implicated in the pathogenesis of diabetic nephropathy. The role of the ET-B receptor (ETBR) is still unclear. The effect of ETBR deficiency on the progression of diabetic nephropathy in a streptozotocin model was analyzed in four groups: (1) Homozygous ETBR-deficient (ETBRd) diabetic rats, (2) ETBRd rats, (3) diabetic controls, and (4) wild-type controls. BP and kidney function were measured for 10 wk, followed by biochemical and histologic analysis of the kidneys. The study demonstrates that ETBRd diabetic rats on a normal-sodium diet develop severe hypertension, albuminuria, and a mild reduction of creatinine clearance. The strong BP rise seems not to be caused by activation of the renin-angiotensin-aldosterone system or by suppression of the nitric oxide system. Elevated plasma ET-1, possibly reflecting a reduced ETBR-dependent clearance, seems to cause the severe hypertension via the ETA receptor. The results do not support the hypothesis that a reduction of ETBR activity inhibits the progression of diabetic nephropathy. The study demonstrates for the first time that the combination of diabetes and ETBR deficiency causes severe low-renin hypertension with progressive renal failure.

Animals↗
PubMed2006

Activation of soluble guanylate cyclase reverses experimental pulmonary hypertension and vascular remodeling.

BACKGROUND: Severe pulmonary hypertension is a disabling disease with high mortality, characterized by pulmonary vascular remodeling and right heart hypertrophy. Using wild-type and homozygous endothelial nitric oxide synthase (NOS3(-/-)) knockout mice with pulmonary hypertension induced by chronic hypoxia and rats with monocrotaline-induced pulmonary hypertension, we examined whether the soluble guanylate cyclase (sGC) stimulator Bay41-2272 or the sGC activator Bay58-2667 could reverse pulmonary vascular remodeling. METHODS AND RESULTS: Both Bay41-2272 and Bay58-2667 dose-dependently inhibited the pressor response of acute hypoxia in the isolated perfused lung system. When wild-type (NOS3(+/+)) or NOS3(-/-) mice were housed under 10% oxygen conditions for 21 or 35 days, both strains developed pulmonary hypertension, right heart hypertrophy, and pulmonary vascular remodeling, demonstrated by an increase in fully muscularized peripheral pulmonary arteries. Treatment of wild-type mice with the activator of sGC, Bay58-2667 (10 mg/kg per day), or the stimulator of sGC, Bay41-2272 (10 mg/kg per day), after full establishment of pulmonary hypertension from day 21 to day 35 significantly reduced pulmonary hypertension, right ventricular hypertrophy, and structural remodeling of the lung vasculature. In contrast, only minor efficacy of chronic sGC activator therapies was noted in NOS3(-/-) mice. In monocrotaline-injected rats with established severe pulmonary hypertension, both compounds significantly reversed hemodynamic and structural changes. CONCLUSIONS: Activation of sGC reverses hemodynamic and structural changes associated with monocrotaline- and chronic hypoxia-induced experimental pulmonary hypertension. This effect is partially dependent on endogenous nitric oxide generated by NOS3.

Animals↗
PubMed2006

Selective indole-based ECE inhibitors: synthesis and pharmacological evaluation.

Inhibition of the metalloprotease ECE-1 may be beneficial for the treatment of coronary heart disease, cancer, renal failure, and urological disorders. A novel class of indole-based ECE inhibitors was identified by high throughput screening. Optimization of the original screening lead structure 6 led to highly potent inhibitors such as 11, which bears a bisaryl amide moiety linked to the indole C2 position through an amide group. Docking of 11 into a model structure of ECE revealed a unique binding mode in which the Zn center of the enzyme is not directly addressed by the inhibitor, but key interactions are suggested for the central amide group. Testing of the lead compound 6 in hypertensive Dahl S rats resulted in a decrease in blood pressure after an initial period in which the blood pressure remained unchanged, most probably the result of ET-1 already present. Indole derivative 6 also displays a cardio-protective effect in a mouse model of acute myocardial infarction after oral administration. The more potent chloropyridine derivative 9 antagonizes big-ET-1-induced increase in blood pressure in rats at intravenous administration of 3 mg kg-1. All ECE inhibitors of the indole class showed high selectivity for ECE over related metalloproteases such as NEP and ACE. Therefore, these compounds might have further potential as drugs for the treatment of coronary heart diseases.

Aspartic Acid Endopeptidases↗
PubMed2006

NO-independent stimulators and activators of soluble guanylate cyclase: discovery and therapeutic potential.

Soluble guanylate cyclase (sGC) is a key signal-transduction enzyme activated by nitric oxide (NO). Impaired bioavailability and/or responsiveness to endogenous NO has been implicated in the pathogenesis of cardiovascular and other diseases. Current therapies that involve the use of organic nitrates and other NO donors have limitations, including non-specific interactions of NO with various biomolecules, lack of response and the development of tolerance following prolonged administration. Compounds that activate sGC in an NO-independent manner might therefore provide considerable therapeutic advantages. Here we review the discovery, biochemistry, pharmacology and clinical potential of haem-dependent sGC stimulators (including YC-1, BAY 41-2272, BAY 41-8543, CFM-1571 and A-350619) and haem-independent sGC activators (including BAY 58-2667 and HMR-1766).

Animals↗
PubMed2006

Targeting the heme-oxidized nitric oxide receptor for selective vasodilatation of diseased blood vessels.

ROS are a risk factor of several cardiovascular disorders and interfere with NO/soluble guanylyl cyclase/cyclic GMP (NO/sGC/cGMP) signaling through scavenging of NO and formation of the strong oxidant peroxynitrite. Increased oxidative stress affects the heme-containing NO receptor sGC by both decreasing its expression levels and impairing NO-induced activation, making vasodilator therapy with NO donors less effective. Here we show in vivo that oxidative stress and related vascular disease states, including human diabetes mellitus, led to an sGC that was indistinguishable from the in vitro oxidized/heme-free enzyme. This sGC variant represents what we believe to be a novel cGMP signaling entity that is unresponsive to NO and prone to degradation. Whereas high-affinity ligands for the unoccupied heme pocket of sGC such as zinc-protoporphyrin IX and the novel NO-independent sGC activator 4-[((4-carboxybutyl){2-[(4-phenethylbenzyl)oxy]phenethyl}amino) methyl [benzoic]acid (BAY 58-2667) stabilized the enzyme, only the latter activated the NO-insensitive sGC variant. Importantly, in isolated cells, in blood vessels, and in vivo, BAY 58-2667 was more effective and potentiated under pathophysiological and oxidative stress conditions. This therapeutic principle preferentially dilates diseased versus normal blood vessels and may have far-reaching implications for the currently investigated clinical use of BAY 58-2667 as a unique diagnostic tool and highly innovative vascular therapy.

Animals↗
PubMed2005

Novel, selective indole-based ECE inhibitors: lead optimization via solid-phase and classical synthesis.

A novel class of indole-based endothelin-converting enzyme (ECE) inhibitors was identified by high throughput screening. We report systematic optimization of this compound class by means of classical and solid-phase chemistry. Optimized compounds with a bisarylamide side chain at the 2-position of the indole skeleton exhibit low-nanomolar activity on ECE.

Aspartic Acid Endopeptidases↗
PubMed2005

Residues stabilizing the heme moiety of the nitric oxide sensor soluble guanylate cyclase.

Soluble guanylate cyclase, a heterodimer consisting of an alpha- and a heme-containing beta-subunit, is the major receptor for the biological messenger nitric oxide (NO) and is involved in various signal transduction pathways. The heme moiety of the enzyme is bound between the axial heme ligand histidine(105) and the recently identified counterparts of the heme propionic acids, tyrosine(135) and arginine(139). The latter residues together with an invariant serine(137) form the unique heme binding motif Y-x-S-x-R. In this work, we show that replacement of the serine(137) with alanine destabilizes the binding of the heme moiety and impairs NO-mediated soluble guanylate cyclase activation.

Alanine↗
PubMed2005

A cell-based cGMP assay useful for ultra-high-throughput screening and identification of modulators of the nitric oxide/cGMP pathway.

We have established a rapid, homogeneous, cell-based, and highly sensitive assay for guanosine 3'-5'-cyclic monophosphate (cGMP) that is suitable for fully automated ultra-high-throughput screening. In this assay system, cGMP production is monitored in living cells via Ca2+ influx through the olfactory cyclic nucleotide-gated cation channel CNGA2, acting as the intracellular cGMP sensor. A stably transfected Chinese hamster ovary (CHO) cell line was generated recombinantly expressing soluble guanylate cyclase, CNGA2, and aequorin as a luminescence indicator for the intracellular calcium concentration. This cell line was used to screen more than 900,000 compounds in an automated ultra-high-throughput screening assay using 1536-well microtiter plates. In this way, we have been able to identify BAY 58-2667, a member of a new class of amino dicarboxylic acids that directly activate soluble guanylate cyclase. The assay system allows the real-time cGMP detection within living cells and makes it possible to screen for activators and inhibitors of enzymes involved in the nitric oxide/cGMP pathway.

Animals↗
PubMed2004

Stimulation of soluble guanylyl cyclase inhibits mesangial cell proliferation and matrix accumulation in experimental glomerulonephritis.

To date, no specific treatment is established in mesangial proliferative glomerulonephritis in humans. Specific stimulation of soluble guanylyl cyclase (sGC), an enzyme catalyzing the synthesis of cGMP from GTP, can be achieved by the novel pyrazolopyridine derivative BAY 41-2272. The effect of sGC stimulation via BAY 41-2272 on mesangial proliferation was assessed in vivo using a mesangial proliferative glomerulonephritis model in rats (anti-Thy1 model). Renal biopsies, as well as glomerular isolates, urine samples, and blood samples were compared in BAY 41-2272- and placebo-treated groups during anti-Thy1 nephritis. The sGC beta(1)-subunit is upregulated during anti-Thy1 nephritis and mainly confined to mesangial areas by immunohistochemistry. Specific therapeutic sGC stimulation during anti-Thy1 nephritis in vivo was achieved via BAY 41-2272 treatment as demonstrated by increased glomerular cGMP levels causing inhibition of mesangial proliferation, glomerular matrix accumulation, and proteinuria compared with placebo-treated animals. sGC is tightly regulated in glomeruli during experimental glomerulonephritis. Considering its beneficial antiproliferative, antifibrotic, and antiproteinuric effect in experimental glomerulonephritis, the therapeutic stimulation of sGC could become a promising future goal in mesangial proliferative glomerulonephritis in humans.

Animals↗
PubMed2004

Relaxin is an independent risk factor predicting death in male patients with end-stage kidney disease.

BACKGROUND: Patients with end-stage kidney disease (ESKD) have a reduced life expectancy mainly as the result of cardiovascular diseases. Relaxin has been implicated in the pathogenesis of cardiovascular diseases. We analyzed the impact of relaxin on death in patients with ESKD. METHODS AND RESULTS: Patients (n =245; 122 women, 123 men) on long-term hemodialysis were followed for 1140 days for death. Blood samples for analysis of relaxin, C-reactive protein, Troponin T, cholesterol, HDL, brain natriuretic peptide, and albumin were taken at study entry. Survival was compared by the Kaplan-Meier method and Cox regression analysis. One hundred seven patients died during the observation period; 66 died of cardiovascular diseases and 28 died of infectious diseases. Elevated serum relaxin concentrations (greater than median) predicted death in male but not in female patients with ESKD: All-cause death (men: relative risk, 2.63; 95% CI, 1.34 to 5.12; P=0.005; women: relative risk, 0.671; 95% CI, 0.33 to 1.35; P=0.262) and cardiovascular death (men: relative risk, 2.95; 95% CI, 1.20 to 7.21; P=0.018; women: relative risk, 0.639; 95% CI, 0.26 to 1.56; P=0.324). CONCLUSIONS: Relaxin is an independent risk factor predicting death in male patients with ESKD on chronic hemodialysis.

Aged↗
PubMed2004

New antithrombotics with an indazole structure.

Fifteen new indazole derivatives have been synthesized. In the Born test, compounds (4f) and (4g) were most active. They inhibited the blood platelet aggregation induced by collagen with an IC(50) = 85 or 90 microM, respectively. After oral administration to rats (60 mg/kg) three of the compounds significantly inhibited the formation of thrombi in arterioles and venules. The strongest effect was observed with (4j) which showed an inhibition of 15% in arterioles and 7% in venules. Further experiments showed that compound (4j) does not mediate these effects by activating soluble guanylate cyclase, but likely by inhibiting phosphodiesterase isoform PDE 5.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2004

Elevated plasma human urotensin-II-like immunoreactivity in ischemic cardiomyopathy.

BACKGROUND: The recently discovered, vasoactive, cyclic undecapeptide human urotensin-II (hU-II), and its G-protein coupled receptor (GPR14) are both expressed in the human cardiovascular system. Little is known about the pathophysiological relevance of hU-II. We hypothesised that circulating hU-II is elevated in patients with coronary artery disease (CAD) corresponding to the degree of cardiac dysfunction. METHODS: 38 patients were diagnosed with coronary artery disease by left heart catheterization, and their functional status was classified according to the New York Heart Association (NYHA). hU-II-like immunoreactivity (hU-II-LI) was measured using a novel specific and sensitive enzyme-linked immunoassay. Calculations were performed with log-transformed hU-II-LI values. RESULTS: hU-II-LI correlated positively with left ventricular end diastolic pressure (LVEDP) (r=0.32, P=0.05) and tended to correlate inversely with left ventricular ejection fraction (LV-EF) (r=-0.31, P=0.061). There was a positive correlation between hU-II-LI and NYHA class (r=0.53, P=0.001). Circulating hU-II-LI was significantly higher in patients with NYHA class III (4822+/-723 pg/ml, N=13) than in patients with class I (1884+/-642 pg/ml, N=9, P=0.007) or class II (2294+/-426 pg/ml, N=15, P=0.046). There was no difference between classes I and II (P=0.83). Furthermore, hU-II-LI correlated significantly with B-type natriuretic peptide, a marker for heart failure (r=0.40, P=0.025). In a linear regression analysis, NYHA class was the only significant independent predictor of hU-II-LI. CONCLUSIONS: The present study demonstrates that plasma hU-II-LI rises significantly in proportion to parameters of cardiac dysfunction and functional impairment in patients with coronary artery disease. These results suggest a pathophysiological role for hU-II in cardiac disease and warrant further investigation.

Biomarkers↗
PubMed2003

Identification of residues crucially involved in the binding of the heme moiety of soluble guanylate cyclase.

Soluble guanylate cyclase (sGC), a heterodimeric hemeprotein, is the only receptor for the biological messenger nitric oxide (NO) identified to date and is intimately involved in various signal transduction pathways. By using the recently discovered NO- and heme-independent sGC activator BAY 58-2667 and a novel cGMP reporter cell, we could distinguish between heme-containing and heme-free sGC in an intact cellular system. Using these novel tools, we identified the invariant amino acids tyrosine 135 and arginine 139 of the beta(1)-subunit as crucially important for both the binding of the heme moiety and the activation of sGC by BAY 58-2667. The heme is displaced by BAY 58-2667 due to a competition between the carboxylic groups of this compound and the heme propionic acids for the identified residues tyrosine 135 and arginine 139. This displacement results in the release of the axial heme ligand histidine 105 and to the observed activation of sGC. Based on these findings we postulate a signal transmission triad composed of histidine 105, tyrosine 135, and arginine 139 responsible for the enzyme activation by this compound and probably also for transducing changes in heme status and porphyrin geometry upon NO binding into alterations of sGC catalytic activity.

Amino Acid Sequence↗
PubMed2003

Mechanisms of nitric oxide independent activation of soluble guanylyl cyclase.

The heterodimeric heme-protein soluble guanylyl cyclase (sGC) is the only proven receptor for nitric oxide (NO). Recently, two different types of NO-independent soluble guanylyl cyclase stimulators have been discovered. The heme-dependent stimulator 2-[1-[2-fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl]-5(4-morpholinyl)-4,6-pyrimidinediamine (BAY 41-8543) stimulates the enzyme in a synergistic fashion when combined with NO, requires the presence of the heme group and can be blocked by the soluble guanylyl cyclase inhibitor 1H-(1,2,4)-Oxadiazole-(4,3-a)-quinoxalin-1-one (ODQ). The heme-independent activator 4-[((4-carboxybutyl)[2-[(4-phenethylbenzol) oxy]phenethyl]amino)methyl[benzoic]acid (BAY 58-2667) activates soluble guanylyl cyclase even in the presence of ODQ or rendered heme-deficient. In the present study, BAY 41-8543, BAY 58-2667 and NO strongly increased V(max). Combination of BAY 58-2667 and NO increased V(max) in an additive manner, whereas the synergistic effect of BAY 41-8543 and NO on enzyme activation was reflected in an overadditive increase of V(max). ODQ potentiated V(max) of BAY 58-2667-stimulated soluble guanylyl cyclase. BAY 41-8543 prolonged the half-life of the nitrosyl-heme complex of NO-activated enzyme, an effect that was not observed with BAY 58-2667. These results show the different activation patterns of both compounds and demonstrate their value as tools to investigate the mechanisms that underlie soluble guanylyl cyclase activation.

Benzoates↗