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Biomedical subjects

S Rosenkranz

Publications and source records attributed to S Rosenkranz.

At least 19 recordsLinked to original sources
PubMed2006

[Pulmonary hypertension: classification, pathophysiology and noninvasive diagnosis].

Pulmonary hypertension (PH) is a serious disease with a poor prognosis. Pulmonary arterial hypertension (PAH) is distinguished from other forms of PHT. The leading symptom is exertional dyspnea. Patients with chronic severe PAH commonly die of right heart failure. PH has a complex heterogeneous aetiology, and precapillary forms are distinguished from postcapillary PH. A number of pathogenetically important signaling pathways such as the endothelin, nitric oxide and prostacyclin pathways have been identified, which constitute the target of the currently approved treatment options. Transthoracic echocardiography is the most important noninvasive diagnostic method. In addition, 6-min walking distance and measurement of serum markers, such as brain natriuretic peptide (BNP), are diagnostically useful and of prognostic significance.

Diagnosis, Differential↗
PubMed2006

[Future aspects of the treatment of pulmonary arterial hypertension].

In addition to combination treatment of pulmonary artery hypertension (PHT) with currently available drug options (endothelin-receptor inhibitors, phosphodiesterase-5 inhibitors, prostanoids). Numerous new drugs of other substance groups are being tested in preclinical and clinical studies. Most of the newly tried drugs use previously identified mechanisms of action that are involved in the development and progression of the underlying vascular disease. This has led to a certain paradigm shift which, in addition to vasodilatation and anti-platelet aggregation treatment, increasingly focuses on antiproliferative effects with the aim of preventing or regressing vascular remodelling. Of particular interest in this connection are tyrosine kinase inhibitors, which inhibit the action of such peptide growth factors as platelet-derived growth factor. Imatinib, one of this class of action, has given promising results in experimental studies and several case reports. Another greatly promising approach in the treatment of PHT are activators and simulators of soluble guanylyl cyclase, which are also currently being investigated in clinical trials.

Animals↗
PubMed2006

Nondispersive fermi arcs and the absence of charge ordering in the pseudogap phase of Bi2Sr2CaCu2O8+delta.

The autocorrelation of angle resolved photoemission data from the high temperature superconductor Bi(2)Sr(2)CaCu(2)O(8+delta) shows distinct peaks in momentum space which disperse with binding energy in the superconducting state, but not in the pseudogap phase. Although it is tempting to attribute a nondispersive behavior in momentum space to charge ordering, a deconstruction of the autocorrelation reveals that the nondispersive peaks arise from the tips of the Fermi arcs, which themselves do not change with binding energy.

Journal Article↗
PubMed2006

First-order metal-insulator transitions in manganites: are they universal?

Conductivity data for La(2-2x)Sr(1+2xMn2O7 (x = 0.6) show a first-order transition from an orbital- or charge-ordered insulator to a metal as the temperature falls below approximately 160 K. The change in conductivity is 100 times larger than that seen previously in any single-phase manganite in zero field. The metallic low-temperature state is similar to x = 0.58, but x = 0.58 shows no evidence of orbital or charge order. This result supports a conclusion that strongly coupled magnetic-conductive transitions are first order.

Journal Article↗
PubMed2006

Nanomagnetic droplets and implications to orbital ordering in LA(1-x)Sr(x)CoO3.

Inelastic cold-neutron scattering on LaCoO3 provided evidence for a distinct low energy excitation at 0.6 meV coincident with the thermally induced magnetic transition. Coexisting strong ferromagnetic (FM) and weaker antiferromagnetic correlations that are dynamic follow the activation to the excited state, identified as the intermediate S = 1 spin triplet. This is indicative of dynamical orbital ordering favoring the observed magnetic interactions. With hole doping as in La(1-x)Sr(x)CoO3 , the FM correlations between Co spins become static and isotropically distributed due to the formation of FM droplets. The correlation length and condensation temperature of these droplets increase rapidly with metallicity due to the double exchange mechanism.

Journal Article↗
PubMed2004

Orbital and Spin Chains in ZnV2O4.

Our powder inelastic neutron scattering data indicate that ZnV2O4 is a system of spin chains that are three-dimensionally tangled in the cubic phase above 50 K due to randomly occupied t(2g) orbitals of V3+ (3d(2)) ions. Below 50 K in the tetragonal phase, the chains become straight due to antiferro-orbital ordering. This is evidenced by the characteristic wave vector dependence of the magnetic structure factor that changes from symmetric to asymmetric at the cubic-to-tetragonal transition.

Journal Article↗
PubMed2004

[Long-term effects of sildenafil in a patient with scleroderma-associated pulmonary hypertension and Raynaud's syndrome].

HISTORY: A 65-year-old woman was admitted because of dyspnea at rest and peripheral edema due to scleroderma-associated pulmonary fibrosis and hypertension, as well as Raynaud's phenomenon. DIAGNOSTIC FEATURES, TREATMENT AND COURSE: She had a marked restrictive ventilatory disorder with severe impairment of diffusion capacity. Right heart catheterization demonstrated a mean pulmonary artery pressure of 50 mmHg. She was able to walk only 220 m. All usual methods of treatment failed to give satisfactory results so that sildenafil (phospherodiesterase type-5 |PDE-5| inhibitor; Viagra ((R)) was given, even though it is not licensed for this indications ("off-label", as a therapeutic attempt. This achieved definite reduction in pulmonary arterial pressure and significantly improved the clinical symptoms. In particular, it drastically reduced the level of atrial natriuretic peptide, an important prognostic marker in right heart failure. Sildenafil also significantly raised peripheral perfusion and the signs of Raynaud's syndrome. CONCLUSION: PDE-5 inhibitors are efficacious in scleroderma-associated pulmonary hypertension and may also provide a new option in the treatment of Raynaud's disease.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2003

[Thin-walled apical ventricular aneurysm associated with hypertrophic obstructive cardiomyopathy].

HISTORY AND ADMISSION FINDINGS: A 73-year-old patient presented for routine follow-up examination for pre-diagnosed hypertrophic obstructive cardiomyopathy (HOCM). The patient's history included arterial hypertension and dyspnea on exertion. INTERVENTIONS: Echocardiography revealed a large apical aneurysm, which had vastly increased in size over the past six months. Further evaluation by cardiac magnetic resonance (NMR) imaging confirmed the aneurysm and demonstrated a wall thickness of no more than 2 mm. TREATMENT AND COURSE: Due to the rapid increase in size in addition to the extremely thin wall diameter the risk of spontaneous rupture was considered high and the patient was referred to surgical therapy. Echocardiographic and NMR-findings were confirmed intraoperatively. The aneurysm was resected and the postoperative progress was uneventful. CONCLUSION: Aneurysms of the apical left ventricle can result from an underlying HOCM. In case of rapid increase of the aneurysm, aneurysmectomy should be performed.

Aged↗
PubMed2003

Crossover from coherent to incoherent electronic excitations in the normal state of Bi(2)Sr(2)CaCu(2)O(8+delta).

Angle resolved photoemission spectroscopy (ARPES) and resistivity measurements are used to explore the overdoped region of the high temperature superconductor Bi(2)Sr(2)CaCu(2)O(8+delta). We find evidence for a new crossover line in the phase diagram between a coherent metal phase, for lower temperatures and higher doping, and an incoherent metal phase, for higher temperatures and lower doping. The former is characterized by two well-defined spectral peaks in ARPES due to coherent bilayer splitting and superlinear behavior in the resistivity, whereas the latter is characterized by a single broad spectral feature in ARPES and a linear temperature dependence of the resistivity.

Journal Article↗
PubMed2003

[A 41 year-old male patient with fever of unknown origin and bacteremia with actinobacillus actinomycetemcomitans].

A 41-year-old male patient presented with fever of unknown origin which had been present for 5 months. The primary diagnostic procedures did not identify an infectious focus. After a lag phase of 13 days, blood cultures became positive for Actinobacillus actinomycetemcomitans, which belongs to the HACEK group of microorganisms. According to the DUKE criteria, infective endocarditis was diagnosed despite negative transesophageal echocardiography (TEE). The sensitivity of TEE is estimated between 86 and 94%. An infected tooth was extracted as a possible focus, and the patient was treated with i.v. antibiotics for 5 weeks according to the guidelines of the AHA and ACC. The fever was permanently terminated, and the further course of the patient was uneventful. Despite negative TEE, the diagnosis "infective endocarditis" should not be rejected, and blood cultures should be grown for up to 30 days.

Actinobacillus Infections↗
PubMed2002

Spontaneous breaking of time-reversal symmetry in the pseudogap state of a high-Tc superconductor.

A change in 'symmetry' is often observed when matter undergoes a phase transition-the symmetry is said to be spontaneously broken. The transition made by underdoped high-transition-temperature (high-Tc) superconductors is unusual, in that it is not a mean-field transition as seen in other superconductors. Rather, there is a region in the phase diagram above the superconducting transition temperature Tc (where phase coherence and superconductivity begin) but below a characteristic temperature T* where a 'pseudogap' appears in the spectrum of electronic excitations. It is therefore important to establish if T* is just a cross-over temperature arising from fluctuations in the order parameter that will establish superconductivity at Tc (refs 3, 4), or if it marks a phase transition where symmetry is spontaneously broken. Here we report that, for a material in the pseudogap state, left-circularly polarized photons give a different photocurrent from right-circularly polarized photons. This shows that time-reversal symmetry is spontaneously broken below T*, which therefore corresponds to a phase transition.

Journal Article↗
PubMed2002

Myocardial fibrosis in transforming growth factor-beta(1) (TGF-beta(1)) transgenic mice is associated with inhibition of interstitial collagenase.

BACKGROUND: TGF-beta(1) mediates effects on fibroblast proliferation and collagen synthesis in the myocardium. The extracellular matrix remodeling depends on the fibrillar collagen degrading matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). The in vivo effects of TGF-beta(1) on the MMP/TIMP system in TGF-beta(1) overexpressing transgenic mice were studied. METHODS: Male Alb/TGF-beta(1)(cys(223,225)ser) transgenic mice (TG) and nontransgenic controls (C; 8 weeks) were examined. Protein expression of collagen type I, -III, interstitial collagenase (Int Coll), MMP-2, -9, TIMP-1, -2, -4 and TGF-beta(1) as well as enzyme activity (MMP-2, -9) were measured (Western blots, zymographic assays). mRNA expression of the interstitial collagenase and MMP-9 was studied with the Light-Cycler based real-time PCR. RESULTS: Overexpression of TGF-beta(1) resulted in a 10-fold increase in plasma and a seven-fold increase in myocardial TGF-beta(1) concentrations. Relative heart weights increased (mg g(-1): 7.8 +/- 0.4 vs. 4.8 +/- 0.6, n = 6; P < 0.01) in TG compared to C. Collagen type I and III increased in TG (1.9-fold and 1.7-fold) compared to controls. Interstitial collagenase protein activity (- 91%) and mRNA expression (-75%) in TG were reduced (P < 0.05-P < 0.001). Gelatinase (MMP-2, MMP-9) expression and activity were not significantly alterated. MMP-inhibitors were increased 2.5-fold (TIMP-1, -4) and 6-fold (TIMP-2) in TG. CONCLUSIONS: TGF-beta(1) produces myocardial fibrosis in vivo. This effect is not only produced by a stimulation of matrix protein formation: a complex regulation of MMP and TIMP interaction, namely decrease of expression and activity of interstitial collagenase and an enhanced inhibition by increased levels of TIMPs, are involved. These mechanisms are optional targets for therapeutic interventions in myocardial diseases.

Animals↗
PubMed2001

[Interaction between sildenafil and antihypertensive drugs: what is evidence-based?].

Hypertension is an important risk factor for erectile dysfunction (ED). Consequently, there is a high coincidence between hypertension and ED. Oral sildenafil (Viagra) is an effective treatment for ED in patients with treated or untreated hypertension. The most common adverse events of sildenafil (headache, flushing, hypotension) result from its moderate vasodilating properties. The concomitant use of sildenafil and organic nitrates is contraindicated because it may lead to a potentiation of the decreases in blood pressure and thus cause life-threatening hypotension. In contrast, the concomitant use of sildenafil and different classes of antihypertensive agents (beta-blockers, alpha-blockers, diuretics, ACE inhibitors, calcium antagonists) may lead to additive but not to potentiating blood pressure decreases. Thus, this combination is unlikely to cause clinically significant hypotension or an increased incidence of adverse events. Sildenafil is an effective and well-tolerated treatment for ED in patients taking concomitant antihypertensive medication, including those on multidrug regimens.

Adult↗