The cobalt way to angucyclinones: asymmetric total synthesis of the antibiotics (+)-rubiginone B2, (-)-tetrangomycin, and (-)-8-O-methyltetrangomycin

A cobalt(I)-mediated convergent and asymmetric total synthesis of angucyclinones with an aromatic B ring has been developed. In the course of our research, we synthesized three naturally occurring anguclinone derivatives, namely, (+)-rubiginone B(2) (1), (-)-8-O-methyltetrangomycin (2), and (-)-tetrangomycin (3). By combining 3-hydroxybenzoic acid, 3-methoxybenzoic acid, citronellal, and geraniol as starting materials in a convergent way, we were able to synthesize chiral triyne chains, which were cyclized with [CpCo(C(2)H(4))(2)] (Cp=cyclopentadienyl) by means of an intramolecular [2+2+2] cycloaddition to their corresponding tetrahydrobenzo[a]anthracenes. Successive oxidation and deprotection steps led to the above-mentioned natural products 1-3.

[Urinary tract infections and Urolithiasis]

The classic "infection stone" struvite is formed as a result of metabolic activity of urease-positive bacteria from alkaline urine with pH-values above 7.5. Due to improved infection diagnostics and antibiotic therapy, the occurrence of infection-related urinary stones in the western industrialized world decreases, despite the generally increasing prevalence rates of urolithiasis in these societies. Struvite is often associated with other mineral phases. These accessory mineral phases could indicate other, non-infection-related causes of urinary stone formation. Thus, mineral analysis is always recommended. Struvite stones as well as struvite encrustations on urinary tract implants are characterized by rapid growth. The rapid growth-related embedding of urease-positive bacteria in the crystalline material makes the urinary stone a persistent source of recurrent urinary tract infections. According to the German Society of Urology guidelines on urolithiasis, a patient with the diagnosis "infection stone" should be assigned to the "high-risk" patient group. Complete stone and debris removal, as well as a special metaphylaxis strategy are required to initiate successful stone therapy.

Sphingosine-1-phosphate-dependent activation of p38 MAPK maintains elevated peripheral resistance in heart failure through increased myogenic vasoconstriction

RATIONALE

Mechanisms underlying vasomotor abnormalities and increased peripheral resistance exacerbating heart failure (HF) are poorly understood.

OBJECTIVE

To explore the role and molecular basis of myogenic responses in HF.

METHODS AND RESULTS

10 weeks old C57Bl6 mice underwent experimental myocardial infarction (MI) or sham surgery. At 1 to 12 weeks postoperative, mice underwent hemodynamic studies, mesenteric, cerebral, and cremaster artery perfusion myography and Western blot. Organ weights and hemodynamics confirmed HF and increased peripheral resistance after MI. Myogenic responses, ie, pressure-induced vasoconstriction, were increased as early as 1 week after MI and remained elevated. Vasoconstrictor responses to phenylephrine were decreased 1 week after MI, but not at 2 to 6 weeks after MI, whereas those to endothelin (ET)-1 and sphingosine-1-phosphate (S1P) were increased at all time points after MI. An antagonist (JTE-013) for the most abundant S1P receptor detected in mesenteric arteries (S1P(2)R) abolished the enhanced myogenic responses of HF, with significantly less effect on controls. Mice with genetic absence of sphingosine-kinases or S1P(2)R (Sphk1(-/-); Sphk1(-/-)/Sphk2(+/-); S1P(2)R(-/-)) did not manifest enhanced myogenic responses after MI. Mesenteric arteries from HF mice exhibited increased phosphorylation of myosin light chain, with deactivation of its phosphatase (MLCP). Among known S1P-responsive regulators of MLCP, GTP-Rho levels were unexpectedly reduced in HF, whereas levels of activated p38 MAPK and ERK1/2 (extracellular signal-regulated kinase 1/2) were increased. Inhibiting p38 MAPK abolished the myogenic responses of animals with HF, with little effect on controls.

CONCLUSIONS

Rho-independent p38 MAPK-mediated deactivation of MLCP underlies S1P/S1P(2)R-regulated increases in myogenic vasoconstriction observed in HF. Therapeutic targeting of these findings in HF models deserves study.

The value of the ECG for decision-making at first medical contact in the patient with acute chest pain

Background/Objectives. Rapid risk stratification of the patient with acute chest pain is essential to select the best management. We investigated the value of the ECG at first medical contact to determine size of the ischaemic myocardial area and thereby severity of risk.Methods. In 386 patients with acute chest pain, ECG findings were correlated with the coronary angiogram. Using ST-segment deviation patterns the location of the coronary culprit lesion was predicted and thereby size of the area at risk. Four groups of patients were present. Those with a narrow QRS and a total 12-lead ST-segment deviation score of >/=5 mm (group 1) or /=120 ms (group 3), and patients with previous coronary bypass grafting (CABG) or percutaneous coronary intervention (PCI) (group 4).Results. Correct coronary culprit lesion localisation was possible in 84% of the 185 patients in group 1, 40% of the total cohort. Accurate prediction was not possible in most patients in groups 2, 3 and 4, in spite of extensive coronary artery disease in group 3 and 4. Conclusions. Using the 12-lead ECG the size of the myocardial area at risk can be accurately predicted when the total ST-segment deviation score is >/=5 mm, allowing identification of those in need of a PCI. In most patients with bundle branch block, previous CABG or PCI, the ECG can not localise the culprit lesion. This approach simplifies and accelerates decision-making at first medical contact. (Neth Heart J 2010;18:301-6.).

Mitral valve disease as well as uncommon extensive epipericardial and intramyocardial calcification secondary to massive mitral annular calcification

A 71-year-old woman with a history of childhood pulmonary tuberculosis was admitted to our hospital for exertional dyspnoea (NYHA functional class II). Transthoracic and transoesophageal echocardiography demonstrated moderate to severe mixed mitral valve disease due to massive mitral annular calcification (MAC) and extensive infiltrative calcification of the atrioventricular groove. In addition, a very uncommon intramyocardial calcification of the ventricular septum and the lateral free wall was diagnosed. This case demonstrates a rare combination of mitral valve disease secondary to MAC, and a small hypertrophied left ventricle, as well as epipericardial and myocardial calcification likely due either to the massive MAC with myocardial extension or to former tuberculous perimyocarditis. The multidimensional imaging approach, which has been used in this particularly case, provided an excellent visualization and clinical evaluation of this rare finding.

The phosphorylation motif at serine 225 governs the localization and function of sphingosine kinase 1 in resistance arteries

OBJECTIVE

The purpose of this study was to characterize a phosphorylation motif at serine 225 as a molecular switch that regulates the pressure-dependent activation of sphingosine kinase 1 (Sk1) in resistance artery smooth muscle cells.

METHODS AND RESULTS

In isolated hamster gracilis muscle resistance arteries, pressure-dependent activation/translocation of Sk1 by ERK1/2 was critically dependent on its serine 225 phosphorylation site. Specifically, expression of Sk1(S225A) reduced resting and myogenic tone, resting Ca(2+), pressure-induced Ca(2+) elevations, and Ca(2+) sensitivity. The lack of function of the Sk1(S225A) mutant could not be entirely overcome by forced localization to the plasma membrane via a myristoylation/palmitylation motif; the membrane anchor also significantly inhibited the function of the wild-type Sk1 enzyme. In both cases, Ca(2+) sensitivity and myogenic tone were attenuated, whereas Ca(2+) handling was normalized/enhanced. These discrete effects are consistent with cell surface receptor-mediated effects (Ca(2+) sensitivity) and intracellular effects of S1P (Ca(2+) handling). Accordingly, S1P(2) receptor inhibition (1 micromol/L JTE013) attenuated myogenic tone without effect on Ca(2+).

CONCLUSIONS

Translocation and precise subcellular positioning of Sk1 is essential for full Sk1 function; and two distinct S1P pools, proposed to be intra- and extracellular, contribute to the maintenance of vascular tone.

Inotropic therapy for cardiac low output syndrome: comparison of hemodynamic effects of dopamine/dobutamine versus dopamine/dopexamine

OBJECTIVE

To examine the effects of a therapy with dopexamine/dopamine in comparison with a regimen of dobutamine/dopamine on the outcome of patients with profound cardiogenic shock.

MATERIAL AND METHODS

Twenty patients presenting with an acute cardiogenic shock assisted with mechanical ventilation, being refractory to a therapy with dopamine alone were analyzed. After persistence of low cardiac output syndrome (cardiac index <2.5 l/min/m2) was confirmed, patients were treated either with receiving dopexamine (2 microg/kg/min) (group 1) or dobutamine (6 microg/kg/min) (group 2) in combination with dopamine (6 microg/kg/min) for 24 hrs. Hemodynamic parameters, urine production and clinical outcome were measured at intervals throughout the study. The groups were similar with respect to demographics and risk factors and there were no significant differences in the supportive treatment and hemodynamics at baseline.

RESULTS

The dopexamine treated patients had lower myocardial oxygen consumption (9310+/-2243 mmHg O2/sec vs. 10621+/-2552 mmHg O2/sec) and lower mean arterial pressure (66+/-11 mmHg vs. 71+/-10 mmHg) after the 24 hrs treatment interval, but no one of the changes reached statistical significance. No differences were found between the two groups for other variables and the overall clinical outcome.

CONCLUSION

The present study revealed that neither substance is superior in the treatment of cardiogenic shock, even if the effect on myocardial consumption and the reported beneficial effects on renal and splanchnic functions might favour the use of dopexamine under certain circumstances.

[Coating with plasma-deposited functionalized diamond-like carbon to decrease encrustations on urological implants]

The double-J stents used today for palliative artificial urinary diversion very often show extreme formation of encrustations, even a short time after implantation. Despite increased scientific material development, the complication rate has not really been strongly influenced. Grant-aided by the German Federal Ministry of Education and Research, we chose a new interdisciplinary and translational approach by coating standard stent materials with plasma-deposited amorphous diamond-like carbon. These stents show clearly reduced rates of encrustation in vitro. Ongoing clinical trials demonstrate a further enhancement of this effect in vivo. The underlying mechanisms are being investigated by extending the established in vitro model, thereby pushing research in this field to a new level.

Inotropic therapy for cardiac low output syndrome: comparison of hemodynamic effects of dopamine/dobutamine versus dopamine/dopexamine

OBJECTIVE

To examine the effects of a therapy with dopexamine/dopamine in comparison with a regimen of dobutamine/dopamine on the outcome of patients with profound cardiogenic shock.

MATERIAL AND METHODS

Twenty patients presenting with an acute cardiogenic shock assisted with mechanical ventilation, being refractory to a therapy with dopamine alone were analyzed. After persistence of low cardiac output syndrome (cardiac index <2.5 l/min/m2) was confirmed, patients were treated either with receiving dopexamine (2 microg/kg/min) (group 1) or dobutamine (6 microg/kg/min) (group 2) in combination with dopamine (6 microg/kg/min) for 24 hrs. Hemodynamic parameters, urine production and clinical outcome were measured at intervals throughout the study. The groups were similar with respect to demographics and risk factors and there were no significant differences in the supportive treatment and hemodynamics at baseline.

RESULTS

The dopexamine treated patients had lower myocardial oxygen consumption (9310 +/- 2243 mmHg O2/sec vs. 10621 +/- 2552 mmHg O2/sec) and lower mean arterial pressure (66 +/- 11 mmHg vs. 71 +/- 10 mmHg) after the 24 hrs treatment interval, but no one of the changes reached statistical significance. No differences were found between the two groups for other variables and the overall clinical outcome.

CONCLUSION

The present study revealed that neither substance is superior in the treatment of cardiogenic shock, even if the effect on myocardial consumption and the reported beneficial effects on renal and splanchnic functions might favour the use of dopexamine under certain circumstances.

Non-determinable defibrillation threshold and inefficacy of implantable cardioverter/defibrillator shocks due to defective connections of the defibrillator lead terminals in the device header port

Inefficacy of implantable cardioverter/defibrillator (ICD) shocks or inappropriate shocks in ICD patients may occur due to mechanical or technical failure of the device. In our unusual case of ICD defibrillation failure, faulty insertion and configuration of the defibrillation lead in the header port resulted in ineffective shock therapies and a non-determinable defibrillation threshold. In cases of successless defibrillations during or after ICD implantation, this problem should be considered.

[Acute cardiogenic shock with inferior myocardial infarction associated with an abnormal origin of the coronary arteries]

HISTORY

A 45-year-old previously healthy man was admitted as an emergency having suddenly gone into cardiogenic shock. He had not been on any medications. The only known risk factor for cardiovascular disease was heavy smoking.

INVESTIGATION AND DIAGNOSIS

The patient was awake and responsive on admission but showed early signs of cardiogenic shock with hypotension (systolic blood pressure 70 mmHg) and a peripheral pulse rate of 25 beats/min, cold sweat, peripheral cyanosis, nausea and retching. A 12-lead electrocardiogram revealed a bradycardic idioventricular rhythm with a wide QRS and monophasic ST segment elevation in the inferior and posterolateral leads.

TREATMENT AND COURSE

The patient required resuscitation immediately after admission because of ventricular fibrillation and was intubated. Cardiopulmonary measures of resuscitation had to be continued while an emergency coronary angiography was performed. This demonstrated an anomalous origin of both coronary arteries from the right sinus of Valsalva and proximal occlusion of a dominant right coronary artery (RCA). Several episodes of ventricular fibrillation required repeated DC cardioversion until a regular rhythm was maintained. Closed-chest cardiac compression had to be continued until percutaneous coronary angioplasty had re-established flow in the artery and a long stent had been inserted, with subsequent hemodynamic stabilization and restitution of a normal cardiac rhythm. The patient was extubated 3 days after admission.

CONCLUSION

Sudden onset of cardiogenic shock and extensive monophasic ST elevations in the ECG without clear-cut localization of coronary supply to the infarcted area should bring to mind an atypical coronary supply pattern or possible coronary artery anomaly.

[Plasma-deposited carbon coating on urological indwelling catheters: Preventing formation of encrustations and consecutive complications]

BACKGROUND

Any material placed in the urinary tract is susceptible to the formation of encrustations of crystalline bacterial biofilms. These biofilms cause severe complications in some cases. The strategies used so far for reduction of these complications by surface modifications of the implant material failed to show the expected results.

PATIENTS AND METHODS

In this study, we investigated amorphous carbon coatings (a-C:H) for their ability to effectively reduce or to repress the progressive formation of infection-enhancing crystalline biofilms as new functional surface coatings. In nine patients suffering for several years from stenting, a-C:H-coated ureteral stents were tested in treatment attempts. The current replacement intervals amounted to a mean of 77 days; the principle cause for early replacement was massive stent encrustations associated with symptomatic urinary tract infections.

RESULTS

In total, 20 coated ureteral stents were tested spanning indwelling times between 3 and 4 months. No stent-related complications occurred. In all cases extraordinarily facile handling, less pain during replacement, and markedly increased tolerance were observed. Symptomatic urinary tract infections were reduced by more than 50%. The stents remained virtually free of encrustations.

CONCLUSION

a-C:H coatings are a novel strategy leading to an enhancement of long-term applicability of ureteral stents and catheters and to improved patient comfort.

[Extended metabolic diagnosis of urolithiasis]

PURPOSE

In Germany, urolithiasis, with a frequency of 5 % and a continuously increasing incidence, must be considered as a widespread disease. Ever growing socio-economic expenses have become the focus of attention. The present treatment strategies provide only limited support for the practitioner in evaluating the often complex causes of urolithiasis and in assessing the chosen treatment. A successful treatment with minimal effort requires a general improvement of existing options in prophylaxis as well as metaphylaxis of urolithiasis. For this purpose, detailed examination and interpretation of a stone-former's urinary composition are essential.

MATERIAL AND METHODS

The following two novel and significant methods with rapid and uncomplicated application procedures are presented: 1) The easy-to-perform and accurate determination of the calcium oxalate crystallisation risk from a urine sample using the BONN risk index (BRI) for the most frequently occurring stone type (75 %). 2) Consideration of the chemical depletion of lithogenic components in a urine sample due to in-vivo growing uroliths. This phenomenon, the so-called depletion effect, can be of considerable clinical relevance due to possible determination of false normal urinary parameters.

RESULTS

This review article explains the theoretical background of these methods and the many applications of the novel methods in practice.

CONCLUSIONS

New strategies in stone prevention can help to reduce the extent of urolithiasis in a patient. The BRI enables the practitioner to optimise patient treatment without major effort. Consideration of the stone growth-related alteration of composition improves the interpretation of urine analysis.

Occasional urinary tract infections and urinary depletion effect mask RTA and carbonate-apatite formation in a strong urinary stone former

We report on a female patient with severe bilateral urolithiasis. A once-off stone analysis performed in the past revealed Mg-phosphate. Occasional UTIs were considered to be the sole cause of stone formation. To date, this assumption had not been checked thoroughly, while stone formation in the patient steadily increased. An inpatient metabolic and analytical work up was performed and stone-growth related urinary alteration was taken into account in urinalysis interpretation. No UTI. NH4Cl-loading test indicated RTA. CT revealed calculi in both kidneys. Carbonate-apatite (CAP) dominates stone composition. Computed urinary composition proximal to stones indicates hypercalciuria. In this patient, occasional UTIs (pH) masked the causes of urolithiasis. Lack of updated stone analysis (CAP), metabolic work up (RTA) and improved urinalysis interpretation (hypercalciuria) concealed the true causes of stone formation.

MR-Techniken zur nicht-invasiven Diagnostik des Prostatakarzinoms

The diagnosis of prostate cancer is suggested on the basis of an elevated PSA level, abnormal digital exam, and abnormal transrectal ultrasound. US-guided biopsy is used to confirm the diagnosis, but up to 30% of prostate cancer may be missed with this approach. Meanwhile MR imaging and proton MR spectroscopy have emerged as the most sensitive additional tools for the noninvasive evaluation of prostate cancer. This article reviews the clinical indications for MRI of the prostate and summarizes new techniques such as high field strength (3 tesla) and dynamic contrast-enhanced MRI.