Splenic rupture complicating periinterventional glycoprotein IIb/IIIa antagonist therapy for myocardial infarction in polycythemia vera

Polycythemia vera is a myeloproliferative disorder predisposing to thromboembolic and bleeding complications. We report the case of a patient with polyglobuly, leukocytosis, and thrombocytosis, who suffered from acute ST-segment elevation myocardial infarction due to thrombotic high-grade pre-stent stenosis two months after percutaneous coronary intervention for complex coronary one vessel disease. Following re-PTCA and stent implantation in conjunction with periinterventional GP IIb/IIIa antagonist treatment, the patient was initially symptom free for about two hours before rapidly developing signs of a hemorrhagic shock. An abdominal CT scan showed splenic rupture with massive intraabdominal hemorrhage as a consequence of secondary bleeding into multiple pre-existing splenic infarctions. The patient's condition stabilized after emergency splenectomy. Subsequent bone marrow biopsy revealed the presence of polycythemia vera. Post-operatively, the patient was treated with the anti-platelet agents aspirin and clopidogrel to prevent subacute stent thrombosis. Additionally, cyto-reductive therapy with hydroxyurea was initiated because of a further increase in the platelet count. In patients with polycythemia vera, the indication for treatment with GP IIb/IIIa antagonists should be carefully weighed against the potentially serious bleeding complications. Should treatment be established, a risk stratification using abdominal sonography and bleeding time testing is recommended, while during treatment red blood count, platelet count, coagulation tests, and hemodynamic parameters should be closely monitored.

[Hypertensive emergencies]

Critical cases of high blood pressure are common clinical occurrences that may account for as many as 25% of all medical emergencies. About 75% of these increases in blood pressure can be judged as hypertensive urgencies, 25% are even hypertensive emergency situations. Nevertheless, only less than 1% of the hypertensive population experiences hypertensive urgency or emergency situations. Hypertensive emergencies are defined as acute cardiac, vascular or cerebral target organ damages. In these cases an acute lowering of blood pressure is inevitable. The rate and intensity of blood pressure depression is dependent on the localization of organ damages. For cardiac and vascular damages it is absolutely necessary to lower the blood pressure rapidly to near normal values. On the contrary, cerebral organ damages are better treated by a moderate lowering of blood pressure peaks to slightly increased blood pressure levels. In hypertensive urgencies no target organ damages occur. For these patients a slow lowering of blood pressure values to normal levels is adequate.

A template-free approach for determining the latency of single events of auditory evoked M100

The phase of the complex output of a narrow band Gaussian filter is taken to define the latency of the auditory evoked response M100 recorded by magnetoencephalography. It is demonstrated that this definition is consistent with the conventional peak latency. Moreover, it provides a tool for reducing the number of averages needed for a reliable estimation of the latency. Single-event latencies obtained by this procedure can be used to improve the signal quality of the conventional average by latency adjusted averaging.

Systematic latency variation of the auditory evoked M100: from average to single-trial data

Standard analyses of neurophysiologically evoked response data rely on signal averaging across many epochs associated with specific events. The amplitudes and latencies of these averaged events are subsequently interpreted in the context of the given perceptual, motor, or cognitive tasks. Can such critical timing properties of event-related responses be recovered from single-trial data? Here, we make use of the M100 latency paradigm used in previous magnetoencephalography (MEG) research to evaluate a novel single-trial analysis approach. Specifically, the latency of the auditory evoked M100 varies systematically with stimulus frequency over a well-defined time range (lower frequencies, e.g., 125 Hz, yield up to 25 ms longer latencies than higher frequencies, e.g., 1000 Hz). Here, we show that the complex filtering approach to single-trial analysis recovers this key characteristic of the M100 response, as well as some other important response properties relating to lateralization. The results illustrate (i) the utility of the complex filtering method and (ii) the potential of the M100 latency to be used for stimulus encoding, since the relevant variation can be observed in single trials.

Vasopressinanaloga als Ultima ratio bei einer schweren Intoxikation mit Vasodilatanzien

HISTORY AND CLINICAL FINDINGS

A 78-year-old woman was admitted to the intensive care unit 9 hours after ingestion of 2 g of isosorbitmononitrate, 430 mg of amlodipine, 250 mg of benazepril and 600 mg of mirtazapin in suicidal intent.

INVESTIGATIONS

Clinical findings and invasive monitoring showed signs of a hyperdynamic hemodynamic cardiovascular failure caused by toxic vasodilatation.

TREATMENT AND COURSE

Despite of primary detoxication, intravenous volume infusion with calcium gluconate, glucagon and naloxone and administration (norepinephrine up to 2 micro g/kg/min) no hemodynamic stabilization was achieved. Only when the vasopressin-analogue argipressin was given peripheral vasodilatation was overcome and hemodynamic stabilization resulted. 10 hours after discontinuing argipressin and norepinephrine the patient developed a mesenteric ischemia, and she finally died on the third day after admission.

CONCLUSION

In circulatory shock due to toxic vasodilatation the use of vasopressin analogue argipressin can be helpful as an ultima therapeutic measure in catecholamine refractory shock caused by vasodilatation. Attention must be paid to overwhelming vasoconstrictor effects resulting in mesenteric ischemia.

MEG-analysis using the Hilbert transform

Event-related fields (ERFs) measured by magnetoencephalography (MEG) upon visual stimulation are analysed by Hilbert transformation. The Hilbert transform of real-valued measured ERF is an analytic complex signal, represented by phase and amplitude. The temporal behaviour of the derivative of the phase, i.e. the instantaneous frequency, allows to distinguish time intervals containing meaningful signal from noise. On the basis of both phase and amplitude, energies and latencies of single event ERFs can be determined.

[Therapy of verapamil poisoning with noradrenaline and the phosphodiesterase inhibitor enoximone]

HISTORY

A 40 year old patient was transferred to the intensive care unit five hours after the ingestion of 2.4 g of verapamil.

ADMISSION FINDINGS

Clinical investigation and invasive monitoring showed signs of cardiogenic shock.

THERAPY

Despite primary detoxification and administration of calcium and norepinephrine no adequate cardiovascular stabilization could be achieved. Only when the phosphodiesterase inhibitor enoximone was added, an increase in myocardial inotropy and a stable cardiovascular state was achieved which was also due to the vasoconstrictory effect of norepinephrine overcoming vasodilatation induced by enoximone.

CONCLUSION

Detoxification, calcium supplementation and catecholamines are established therapeutic measures. An additional therapy with phosphodiesterase inhibitors is a promising step in conquering predominant heart failure and hypotension.

[Hypersensitivity syndrome during therapy with allopurinol in asymptomatic hyperuricemia with a fatal outcome]

HISTORY AND ADMISSION FINDINGS

A 86-year-old woman with chronic renal failure was treated with allopurinol for asymptomatic hyperuricemia. After one week she developed quickly progressive exanthema, bullous eruptions, epidermolysis, fever of 39.1; C and dyspnoea at rest.

DIAGNOSIS, TREATMENT AND COURSE

The diagnosis of an allopurinol-induced hypersensitivity syndrome with toxic epidermal necrolysis was made from the history, the typical clinical picture and a skin biopsy. Initial therapy starts with steroids. Because of a lack of clinical improvement therapy was changed to immunoglobulins. In addition, systemic analgesia and cardiocirculatory supportive therapy were given. Because of increasing somnolence and severe pain intubation and controlled artificial ventilation were initiated. Despite intensive therapy progressive multi- organ failure developed and the patient died 3 weeks after start of symptoms.

CONCLUSIONS

The life threatening hypersensitivity syndrome with fever, eosinophilia, hepatitis, renal failure and skin eruptions as severe as epidermal necrolysis is the most dangerous complication of therapy with allopurinol. The trigger seems to be oxipurinol, the main metabolite of allopurinol, which particularly accumulates in patients with renal failure and concomitant therapy with thiazides. There is no specific treatment of the disease. The use of allopurinol in patients with asymptomatic hyperuricaemia is not indicated in most cases. Dose adjustment according to the clearance of creatinine is mandatory.

Neoceptor concept based on molecular complementarity in GPCRs: a mutant adenosine A(3) receptor with selectively enhanced affinity for amine-modified nucleosides

Adenosine A(3) receptors are of interest in the treatment of cardiac ischemia, inflammation, and neurodegenerative diseases. In an effort to create a unique receptor mutant that would be activated by tailor-made synthetic ligands, we mutated the human A(3) receptor at the site of a critical His residue in TM7, previously proposed to be involved in ligand recognition through interaction with the ribose moiety. The H272E mutant receptor displayed reduced affinity for most of the uncharged A(3) receptor agonists and antagonists examined. For example, the nonselective agonist 1a was 19-fold less potent at the mutant receptor than at the wild-type receptor. The introduction of an amino group on the ribose moiety of adenosine resulted in either equipotency or enhanced binding affinity at the H272E mutant relative to wild-type A(3) receptors, depending on the position of the amino group. 3'-Amino-3'-deoxyadenosine proved to be 7-fold more potent at the H272E mutant receptor than at the wild-type receptor, while the corresponding 2'- and 5'-amino analogues did not display significantly enhanced affinities. An 3'-amino-N(6)-iodobenzyl analogue showed only a small enhancement at the mutant (K(i) = 320 nM) vs wild-type receptors. The 3'-amino group was intended for a direct electrostatic interaction with the negatively charged ribose-binding region of the mutant receptor, yet molecular modeling did not support this notion. This design approach is an example of engineering the structure of mutant receptors to recognize synthetic ligands for which they are selectively matched on the basis of molecular complementarity between the mutant receptor and the ligand. We have termed such engineered receptors "neoceptors", since the ligand recognition profile of such mutant receptors need not correspond to the profile of the parent, native receptor.

Biotin labelling of amines by polymer-assisted solution-phase synthesis

An efficient and simple polymer-assisted approach has been developed to biotinylate multifunctional compounds bearing an amino functionality. Biotin was immobilized on aminomethylated polystyrene via the Kenner safety catch linker, activated and subsequently transferred to the amino function of the target compounds chemoselectively, thus avoiding protecting group operations. This approach holds potential for the introduction of spacer-modified biotin derivatives.

Aryl rings are part of the darpone pharmacophore

In order to investigate structure-activity relationships in the antiproliferative darpone series, the derivatives 8a and 8b lacking the aryl substituents in either 2- or 4-position were synthesized and evaluated for cancer cell growth inhibition. Since both 8a and 8b were devoid of noteworthy antiproliferative activity, both aryl substituents can be considered as part of the darpone pharmacophore.

Variability of the QRS signal in high-resolution electrocardiograms and magnetocardiograms

The variability of electric and magnetic signals from the heart during the depolarization phase is investigated. A signal processing method is developed, which provides estimates for the beat-to-beat variability of the QRS-complex. The method is based on the decomposition of the depolarization signal into bandpass signals by means of the Morlet wavelet transform. The beat variability of the depolarization signal is estimated by normalized variances of the envelope and instantaneous frequency of bandpass signals. Time intervals of the bandpass filtered depolarization signals having a high signal-to-noise ratio are selected applying an analysis based on phase statistics. The method was tested by computer simulation and experimental data taken from electrocardiographic and magnetocardiographic measurements of healthy persons and patients prone to malignant ventricular tachycardia (VT) or ventricular fibrillation (VF). Results suggest that the calculated variance parameters permit the characterization of beat variable depolarization signals and distinguish VT/VF patients from healthy persons.

[Time series analysis of abnormal heart beat signals]

The variability of electric and magnetic signals from the heart during the depolarization phase is investigated. A signal processing method is developed which provides estimates for the beat-to-beat variability of the QRS-complex. The method is based on the decomposition of the depolarization signal into bandpass signals by means of the Morlet wavelet transform. The beat variability of the depolarization signal is estimated by normalized variances of the envelope and instantaneous frequency of bandpass signals. Time intervals of the bandpass filtered depolarization signals having a high signal-to-noise ratio are selected by applying an analysis based on phase statistics. The method was tested by experimental data taken from ECG and MCG measurements of healthy persons and patients prone to malignant ventricular tachycardia (VT) or ventricular fibrillation (VF). Results suggest that the calculated variance parameters permit the characterization of beat variable depolarization signals and distinguish VT/VF patients from healthy persons. The method developed can be used to obtain additional information concerning abnormal heart signals which is attenuated when applying signal averaging.

Paullones are potent inhibitors of glycogen synthase kinase-3beta and cyclin-dependent kinase 5/p25

Paullones constitute a new family of benzazepinones with promising antitumoral properties. They were recently described as potent, ATP-competitive, inhibitors of the cell cycle regulating cyclin-dependent kinases (CDKs). We here report that paullones also act as very potent inhibitors of glycogen synthase kinase-3beta (GSK-3beta) (IC50: 4-80 nM) and the neuronal CDK5/p25 (IC50: 20-200 nM). These two enzymes are responsible for most of the hyperphosphorylation of the microtubule-binding protein tau, a feature observed in the brains of patients with Alzheimer's disease and other neurodegenerative 'taupathies'. Alsterpaullone, the most active paullone, was demonstrated to act by competing with ATP for binding to GSK-3beta. Alsterpaullone inhibits the phosphorylation of tau in vivo at sites which are typically phosphorylated by GSK-3beta in Alzheimer's disease. Alsterpaullone also inhibits the CDK5/p25-dependent phosphorylation of DARPP-32 in mouse striatum slices in vitro. This dual specificity of paullones may turn these compounds into very useful tools for the study and possibly treatment of neurodegenerative and proliferative disorders.

Polymer-assisted solution-phase synthesis of 2'-amido-2'-deoxyadenosine derivatives targeted at the NAD(+)-binding sites of parasite enzymes

A polymer-assisted solution-phase (PASP) synthesis of lead structure analogues ready for biological testing without the demand for chromatographic purification is described. Carboxylic acids are coupled to the Kenner or Ellman safety catch linker, respectively, activated by methylation or cyanomethylation and subsequently transferred to the 2'-amino group of the 2'-amino-2'-deoxyadenosine scaffold (5). The chemoselective attack of weakly nucleophilic amino groups on the N-alkylated N-acyl sulfonamide linker allows for the synthesis of amides 6 in high yields without the need for protection of primary and secondary hydroxyl functions. Thus, the use of 4-sulfamylbenzoylaminomethyl polystyrene is reported for the construction of chemoselective polymer-supported acylating reagents instead of its known use as linker in solid-phase peptide or organic synthesis. This approach is demonstrated to be well suited to obtain 2'-amido-2'-deoxyadenosine derivatives 6 in parallel format. Biological evaluation of all compounds reported revealed no improvement over known lead structures.

Quantitative MRS: comparison of time domain and time domain frequency domain methods using a novel test procedure

For quantitative analysis of in vivo MR spectra, a state-of-the-art time domain method was compared with a recently reported time domain frequency domain method which uses wavelets for background characterization. The comparison was made on the basis of results for simulated test problems that were constructed by combining measured and simulated MRS data at different signal-to-noise ratios in order to simultaneously reflect real world difficulties, in particular the overlapping background problem, and to allow for quantitative judgment of a method's accuracy. Incorporating prior knowledge was also considered. The results obtained give insight into the accuracy of the methods when applied to measured MRS data. Due to the improved background characterization, the time domain frequency domain method outperformed the time domain method in some of the test cases. Both methods were also applied to serial brain MR spectra of a healthy volunteer on 10 occasions.