Directed, Elliptic, and Higher Order Flow Harmonics of Protons, Deuterons, and Tritons in Au+Au Collisions at sqrt[s_{NN}]=2.4 GeV

Flow coefficients v_{n} of the orders n=1-6 are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons, and tritons as a function of centrality, transverse momentum, and rapidity in Au+Au collisions at sqrt[s_{NN}]=2.4  GeV. Combining the information from the flow coefficients of all orders allows us to construct for the first time, at collision energies of a few GeV, a multidifferential picture of the angular emission pattern of these particles. It reflects the complicated interplay between the effect of the central fireball pressure on the emission of particles and their subsequent interaction with spectator matter. The high precision information on higher order flow coefficients is a major step forward in constraining the equation of state of dense baryonic matter.

Exploring time like tranistions in pp, πp and AA reactions with HADES

Radiative transition of an excited baryon to a nucleon with emission of a virtual massive photon converting to dielectron pair (Dalitz decays) provides important information about baryon-photon coupling at low q2 in timelike region. A prominent enhancement in the respective electromagnetic transition Form Factors (etFF) at q2 near vector mesons ρ/ω poles has been predicted by various calculations reflecting strong baryon-vector meson couplings. The understanding of these couplings is also of primary importance for the interpretation of the emissivity of QCD matter studied in heavy ion collisions via dilepton emission. Dedicated measurements of baryon Dalitz decays in proton-proton and pion-proton scattering with HADES detector at GSI/FAIR are presented and discussed. The relevance of these studies for the interpretation of results obtained from heavy ion reactions is elucidated on the example of the HADES results.

Strong Absorption of Hadrons with Hidden and Open Strangeness in Nuclear Matter

We present the first observation of K^{-} and ϕ absorption within nuclear matter by means of π^{-}-induced reactions on C and W targets at an incident beam momentum of 1.7  GeV/c studied with HADES at SIS18/GSI. The double ratio (K^{-}/K^{+})_{W}/(K^{-}/K^{+})_{C} is found to be 0.319±0.009(stat)_{-0.012}^{+0.014}(syst) indicating a larger absorption of K^{-} in heavier targets as compared to lighter ones. The measured ϕ/K^{-} ratios in π^{-}+C and π^{-}+W reactions within the HADES acceptance are found to be equal to 0.55±0.04(stat)_{-0.07}^{+0.06}(syst) and to 0.63±0.06(stat)_{-0.11}^{+0.11}(syst), respectively. The similar ratios measured in the two different reactions demonstrate for the first time experimentally that the dynamics of the ϕ meson in nuclear medium is strongly coupled to the K^{-} dynamics. The large difference in the ϕ production off C and W nuclei is discussed in terms of a strong ϕN in-medium coupling. These results are relevant for the description of heavy-ion collisions and the structure of neutron stars.

Time-Like Baryon Transitions studies with HADES

The HADES collaboration uses the e+e− production as a probe of the resonance matter produced in collisions at incident energies of 1-3.5 GeV/nucleon at GSI. Elementary reactions provide useful references for these studies and give information on resonance Dalitz decays (R→Ne+e−). Such processes are sensitive to the structure of time-like electromagnetic baryon transitions in a kinematic range where (off-shell) vector mesons play a crucial role. Results obtained in proton-proton reactions and in a commissioning pion-beam experiment are reported and prospects for future pion beam experiments and for first hyperon Dalitz decay measurements are described. The connection with the investigations of medium effects to be continued with HADES in the next years at SIS18 and SIS100 is also discussed.

Anti-FcγRIIB (CD32) Antibodies Differentially Modulate Murine FVIII-Specific Recall Response in vitro

Fc gamma receptors (FcγRs) for IgG regulate adaptive immune responses by modulating activating and inhibitory signalling pathways within immune cells. Data from a haemophilia A mouse model demonstrate that genetic deletion or blockade of the inhibitory FcγR (CD32) suppresses the formation of antibody-secreting cells (ASCs) in vitro. Mechanisms preventing the FVIII-specific recall response, however, remain unclear. Here, the potential role of CD32 inhibition was studied by differentially modulating receptor activity with selected anti-CD32 monoclonal antibodies (mAbs). Splenocytes from immunized FVIII^-/- mice were restimulated with FVIII in the absence or presence of different anti-CD32 mAbs over 6 days. At day 6, cytokine release was quantified from cell culture supernatant and the formation of FVIII-specific ASCs assessed. Binding of FVIII-containing immune complexes (F8-ICs) to bone marrow-derived dendritic cells (BMdDCs) was also investigated. The antagonistic CD32 mAb AT128 suppressed the formation of FVIII-specific ASCs and reduced secretion of IFN-γ and IL-10. In contrast, the agonistic mAbs AT130-2 and AT130-5, and their F(ab')₂ fragments, allowed the formation of FVIII-specific ASCs, even though the full IgG of AT130-2 reduced binding of F8-ICs to CD32. Data suggest that an inhibitory signal is transmitted when F8-ICs bind to CD32 and that this signal is required during memory B cell (MBC) activation to support formation of FVIII-specific ASCs. If the inhibitory signal is lacking due to CD32 deletion or blockade with antagonistic anti-CD32 mAbs, FVIII-specific T cell stimulation and ASC formation are suppressed, whereas agonistic stimulation of CD32 restores T cell stimulation and ASC formation.

Analysis of 161Tb by radiochemical separation and liquid scintillation counting

The determination of ¹⁶¹Tb activity is problematic due to its very low fission yield, short half-life, and the complication of its gamma spectrum. At AWE, radiochemically purified ¹⁶¹Tb solution was measured on a PerkinElmer 1220 Quantulus^TM Liquid Scintillation Spectrometer. Since there was no ¹⁶¹Tb certified standard solution available commercially, the counting efficiency was determined by the CIEMAT/NIST Efficiency Tracing method. The method was validated during a recent inter-laboratory comparison exercise involving the analysis of a uranium sample irradiated with thermal neutrons. The measured ¹⁶¹Tb result was in excellent agreement with the result using gamma spectrometry and the result obtained by Pacific Northwest National Laboratory.

Subthreshold Ξ^{-} production in collisions of p(3.5 GeV)+Nb

Results on the production of the double strange cascade hyperon Ξ^{-} are reported for collisions of p(3.5  GeV)+Nb, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18 at GSI Helmholtzzentrum for Heavy-Ion Research, Darmstadt. For the first time, subthreshold Ξ^{-} production is observed in proton-nucleus interactions. Assuming a Ξ^{-} phase-space distribution similar to that of Λ hyperons, the production probability amounts to P_{Ξ^{-}}=[2.0±0.4(stat)±0.3(norm)±0.6(syst)]×10^{-4} resulting in a Ξ^{-}/(Λ+Σ^{0}) ratio of P_{Ξ^{-}}/P_{Λ+Σ^{0}}=[1.2±0.3(stat)±0.4(syst)]×10^{-2}. Available model predictions are significantly lower than the measured Ξ^{-} yield.

In vivo evaluation of a MR-guided 980nm laser interstitial thermal therapy system for ablations in porcine liver

PURPOSE

To evaluate the use of a 980-nm diode laser for magnetic resonance-guided laser interstitial thermal therapy (MR-guided LITT) ablations in liver tissue in an in vivo porcine model.

MATERIALS AND METHODS

MR-guided guided LITT was performed on nine juvenile pigs placed under general anesthesia. Target ablation sites were selected in the left and right lobes of the liver. Laser applicators were placed in the liver using intermittent MR guidance. Up to four separate ablations were performed in each animal using a 15 or 30 W laser generator using one or two applicators. During the ablations, continuous MR-based temperature mapping (MR-thermal mapping), using a proton resonance frequency technique, was performed to monitor the size of the ablation in real-time. Extent of thermal tissue damage was continuously estimated based on Arrhenius model. Two-minute ablations were performed at each site. MR-thermal mapping of ablations within the posteroinferior liver were accomplished with continuous breathing at low tidal volume. In the mid right lobe of the liver, due to motion artefacts, MR-thermometry was performed intermittently during breath hold periods. In the left lobe of the liver, ablations were performed with ventilation using positive end expiratory pressure (PEEP) of 10 cm of water. Upon completion, MR imaging with gadolinium contrast was performed to assess the extent of treatment. Thermal lesions were subsequently measured using both, MR-thermal dose and MR gadolinium images, for comparison. Following the animal euthanasia, the liver was harvested and subjected to formalin fixation and paraffin embedding for histological examination.

RESULTS

Between one and four focal liver ablations (total 24 ablations) were successfully performed in nine animals with either a 15 or 30 W laser generator. For the 15-W laser generator, the average single applicator ablation size was (2.0 ± 0.5) × (2.6 ± 0.4) cm(2) , as measured by magnetic resonance (MR) thermometry, or (1.7 ± 0.4) × (2.2 ± 0.6) cm(2) , as measured with gadolinium contrast, with the difference being not statistically significant. For the 30-W laser generator, the average single applicator ablation size was (2.4 ± 0.3) × (3.3 ± 0.5) cm(2) by MR thermometry and (2.1 ± 0.4) × (2.9 ± 0.3) cm(2) by gadolinium enhancement, with no statistically significant difference. Simultaneously activating two applicators with the 15 W generator demonstrated ablation sizes of (3.7 ± 0.9) × (3.2 ± 0.1) cm(2) using MR thermometry and (2.3 ± 0.6) × (2.4 ± 0.3) cm(2) with gadolinium contrast, while using two applicators in the 30-W laser generator, yielded (4.5 ± 0.6) × (3.9 ± 0.2) cm(2) using MR thermometry and (4.4 ± 1.1) × (3.6 ± 0.5) cm(2) with gadolinium contrast enhancement.

CONCLUSION

In our experience, we found that liver ablations performed with a MR-guided 980-nm diode LITT system through the saline cooled catheter applicator could be performed throughout the liver. Additionally, liver ablations were safe and produced a clinically applicable ablation zone. These results suggest the 980-nm diode laser MR-guided LITT system could be effective in treatments of hepatic tumors.

Deep subthreshold Xi;{-} production in Ar + KCl reactions at 1.76A GeV

We report first results on a deep subthreshold production of the doubly strange hyperon Xi;{-} in a heavy-ion reaction. At a beam energy of 1.76A GeV the reaction Ar + KCl was studied with the High Acceptance Di-Electron Spectrometer at SIS18/GSI. A high-statistics and high-purity Lambda sample was collected, allowing for the investigation of the decay channel Xi;{-} --> Lambdapi;{-}. The deduced Xi;{-}/(Lambda + Sigma;{0}) production ratio of (5.6 +/- 1.2_{-1.7};{+1.8}) x 10;{-3} is significantly larger than available model predictions.

Hepatic failure after injury - a common pathogenesis with sclerosing cholangitis?

OBJECTIVE

Hepatic failure after trauma occurs in about 5 - 10 % of multiple injured patients. Mortality rate remains high and liver dysfunction might deteriorate to complete liver failure and contribute to multi organ failure (MOF). Pathogenesis is multifactorial and distinct mechanisms are unknown.

METHODS

To get further knowledge about pathogenesis of posttraumatic liver failure we investigated clinical course, inflammatory mediators, ERCP and histologic findings in 7 patients [6 male, 1 female, mean age 45.7 +/- 12.1 years, mean ISS 38.4 +/- 10.8 pts. (range 25-58 pts.)] that evolved hepatic failure after major trauma. Mortality rate was 14 %.

RESULTS

All patients presented with a prolonged shock period after trauma and severe respiratory failure requiring differentiated ventilatory support and prone positioning. Onset of significant bilirubinemia (> 2.0 mg/dl) was day 3 to 16 days (median 11 days) after trauma. Past medical history did not reveal any underlying liver disease in all patients. Pro-and anti-inflammatory parameters like WBC, Procalcitonin, IL-4, IL-10, IL-11, IL-12, and IL-18 remained close to healthy control values. CRP was elevated but did not correlate with Bilirubin. Transaminases (ALT, AST) remained close to normal values but increased during the further course, whereas alkaline phosphatase (aP) and gamma-glutamyl transpeptidase (gGT) were already significantly elevated even before Bilirubin (gammaGT: 394 +/- 317 U/l; controls: < 56 U/l; aP 557 +/- 311 U/l; controls: < 127 U/l). Although no cholestasis was proven in ultrasound and CT investigations, all patients underwent ERCP and liver biopsy. Here, all patients presented uniform signs of multiple strictures of the intrahepatic bile ducts and sclerosing cholangitis.

CONCLUSIONS

Our data provide evidence that sclerosing cholangitis contributes to liver failure after trauma. The pathomorphologic picture can not distinguish between shock liver and sclerosing cholangitis. Ischemia during posttraumatic shock might be an early trigger of hepatic failure, supported by further contributing factors such as catecholamines, parenteral nutrition, and bacterial translocation. As specific therapy for sclerosing cholangitis does not exist yet, prevention of triggers is central to avoid progressive hepatic failure in those patients. Further prospective studies have to prove whether sclerosing cholangitis is commonly involved in the pathogenesis of liver failure after trauma and shock. If so, one might speculate that early therapy with ursodeoxycholic acid might be effective thus reducing incidence and/or severity of hepatic failure in the future.

Dielectron production in 12C+12C collisions at 2A GeV with the HADES spectrometer

The invariant-mass spectrum of e+e- pairs produced in 12C+12C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the pi(0)-Dalitz to the rho/omega invariant-mass region. Dalitz decays of pi(0) and eta account for all the yield up to 0.15 GeV/c(2), but for only about 50% above this mass. A comparison with model calculations shows that the excess pair yield is likely due to baryon-resonance and vector-meson decays. Transport calculations based on vacuum spectral functions fail, however, to describe the entire mass region.

[Polytrauma with severe lung contusion. Early use of extracorporeal membrane oxygenation]

Extracorporeal membrane oxygenation (ECMO) is a technique for sustaining body oxygenation in case of respiratory failure. Since ECMO technology has undergone improvements resulting in better hemo-compatibility and reduced side effects, venovenous ECMO is a mostly accepted treatment of adult respiratory distress syndrome (ARDS). One should discuss the early initiation of ECMO therapy for post-traumatic respiratory failure. We report about a 23-year-old male and a 15-year-old female patient, who suffered polytrauma and received early treatment with ECMO because of severe lung contusion.

Interobserver agreement for the diagnosis of venous thromboembolism on computed tomography chest angiography and indirect venography of the lower extremities in emergency department patients

OBJECTIVES

To determine interobserver agreement between radiologists for computed tomography (CT) angiography and venography. CT venography of the lower extremities combined with standard CT angiography of the chest may result in an increased overall diagnosis rate of venous thromboembolism (pulmonary embolism or deep venous thrombosis).

METHODS

The study had a retrospective cohort design. The population consisted of emergency department patients who were evaluated for suspected pulmonary embolism. A random sample of 50 patients diagnosed and treated for venous thromboembolism and 50 age- and gender-matched patients whose CT angiograms and venograms were read as negative were enrolled. The original reading (R1) was compared with readings of two study radiologists: R2, a general radiologist, and R3, a radiologist with fellowship training in cross-sectional imaging. All readers were blinded to each other.

RESULTS

Both R2 and R3 found both CT angiogram and venogram components technically adequate in 95% (95% CI = 89% to 98%) and 86% (95% CI = 78% to 92%) of studies, respectively. The agreement was very good for CT angiography (lowest agreement = 92%; lowest kappa = 0.83) and was good for CT venography (85%, kappa = 0.65). In nine cases, R1 read the CT angiogram as negative but the venogram as positive for DVT, whereas both R2 and R3 read both components as negative in four of these nine, suggesting a false-positive isolated DVT rate of 44% (95% CI = 19% to 73%). In no case did R1 read both scan components as negative when R2 and R3 agreed on presence of pulmonary embolism or DVT.

CONCLUSIONS

Diagnosis of pulmonary embolism on CT angiography is more reliable than diagnosis of isolated DVT on CT venography.

Prevalence and significance of nonthromboembolic findings on chest computed tomography angiography performed to rule out pulmonary embolism: a multicenter study of 1,025 emergency department patients

OBJECTIVES

To evaluate the hypothesis that computed tomography (CT) angiography often yields a result interpreted as an alternative diagnosis to pulmonary embolism (PE) in emergency department (ED) patients.

METHODS

This was a multicenter, retrospective, and secondary analysis of consecutive patients in three academic emergency departments. ED patients with symptoms suspicious for PE were included. CT angiography was ordered at the discretion of the treating physician; patients were identified by query of the electronic medical record. Board-certified radiologists gave CT readings, which were reviewed by two independent emergency physicians who categorized the non-PE findings into one of four acuity categories: A = requiring specific and immediate intervention, B = requiring specific action on follow-up, C = requiring no action, and D = indeterminate findings.

RESULTS

The prevalence of PE among the 1,025 patients studied was 10% (95% CI = 8% to 12%). In the 921 patients without PE, the mean prevalences (ranges between sites) of concordant categorized non-PE findings were: A = 7% (range 3%-11%), B = 10% (7%-13%), C = 17% (10%-20%), D = 4% (0%-8%), and no ancillary finding = 41% (29% to 45%). The most common category A findings included infiltrate or consolidation suggesting pneumonia (81%), aortic aneurysm or dissection (7%), and mass suggesting undiagnosed malignancy (7%). The overall unweighted agreement was 80% (kappa = 0.72) and weighted agreement was 93% (kappa(w) = 0.84).

CONCLUSIONS

In ED patients with suspected PE, the CT angiogram frequently provides evidence suggesting an important alternative diagnosis to PE. Pulmonary infiltrate suggesting pneumonia was the most common non-PE finding.

Prevalence and significance of nonthromboembolic findings on chest computed tomography angiography performed to rule out pulmonary embolism: a multicenter study of 1,025 emergency department patients

OBJECTIVES

To evaluate the hypothesis that computed tomography (CT) angiography often yields a result interpreted as an alternative diagnosis to pulmonary embolism (PE) in emergency department (ED) patients.

METHODS

This was a multicenter, retrospective, and secondary analysis of consecutive patients in three academic emergency departments. ED patients with symptoms suspicious for PE were included. CT angiography was ordered at the discretion of the treating physician; patients were identified by query of the electronic medical record. Board-certified radiologists gave CT readings, which were reviewed by two independent emergency physicians who categorized the non-PE findings into one of four acuity categories: A = requiring specific and immediate intervention, B = requiring specific action on follow-up, C = requiring no action, and D = indeterminate findings.

RESULTS

The prevalence of PE among the 1,025 patients studied was 10% (95% CI = 8% to 12%). In the 921 patients without PE, the mean prevalences (ranges between sites) of concordant categorized non-PE findings were: A = 7% (range 3%-11%), B = 10% (7%-13%), C = 17% (10%-20%), D = 4% (0%-8%), and no ancillary finding = 41% (29% to 45%). The most common category A findings included infiltrate or consolidation suggesting pneumonia (81%), aortic aneurysm or dissection (7%), and mass suggesting undiagnosed malignancy (7%). The overall unweighted agreement was 80% (kappa = 0.72) and weighted agreement was 93% (kappa(w) = 0.84).

CONCLUSIONS

In ED patients with suspected PE, the CT angiogram frequently provides evidence suggesting an important alternative diagnosis to PE. Pulmonary infiltrate suggesting pneumonia was the most common non-PE finding.

Electrocardiographic findings in Emergency Department patients with pulmonary embolism

To assess the pre-study, null hypothesis that there is no difference in the electrocardiogram (EKG) findings for Emergency Department (ED) patients who rule in vs. rule out for suspected pulmonary embolism, a retrospective review of a cohort of patients with pulmonary embolism and their controls was conducted in an academic, suburban ED. Patients who were evaluated in the ED during a one-year study period for symptoms suggestive of pulmonary embolism were eligible for inclusion. All patients with pulmonary embolism and sex- and age-matched controls comprised the final study groups. Two board-certified cardiologists reviewed each patient's EKG. There were 350 eligible patients identified; 49 patients with pulmonary embolism and 49 controls were entered into the study. The most common rhythm observed in both groups was normal sinus rhythm (67.3% cases vs. 68.6 % controls; p = 1.0). Abnormalities believed to be associated with pulmonary embolism occurred with similar frequency in both case and control groups (sinus tachycardia [18.8 % vs. 11.8%, respectively; p = 0.40]), incomplete right bundle branch block (4.2% vs. 0.0%, respectively; p = 0.24), complete right bundle branch block (4.2% vs. 6.0, respectively; p = 1.0), S1Q3T3 pattern (2.1 vs. 0.0, respectively; p = 0.49), S1Q3 pattern (0.0 vs. 0.0), and extreme right axis (0.0 vs. 0.0). New EKG changes were identified more frequently for patients with pulmonary embolism (33.3% vs. 12.5% controls; p = 0.03), but specific findings were rarely different between cases and controls. In our cohort of ED patients, we did not identify EKG features that are likely to help distinguish patients with pulmonary embolism from those who rule out for the disease.

Kavain, dihydrokavain, and dihydromethysticin non-competitively inhibit the specific binding of [3H]-batrachotoxinin-A 20-alpha-benzoate to receptor site 2 of voltage-gated Na+ channels

The mode of action of the kava pyrones, kavain, dihydrokavain and dihydromethysticin on the specific binding of [3H]-batrachotoxinin-A 20-alpha-benzoate to epitope 2 of voltage-dependent Na+ channels was investigated by performing saturation experiments in the presence and absence of these kava pyrones. The tested compounds significantly decreased the apparent total number of binding sites (Bmax) for [3H]-batrachotoxinin-A 20-alpha-benzoate (control: 0.5 pmol/mg protein, kava pyrones: 0.2-0.27 pmol/mg protein) with little change in the equilibrium constants (KD) for [3H]-batrachotoxin-A 20-alpha-benzoate (control: 28.2 nM, kava pyrones: 24-31 nM). The results indicate for the kava pyrones a non-competitive inhibition of the specific [3H]-batrachotoxinin-A 20-alpha-benzoate binding to receptor site 2 of voltage-gated Na+ channels.

Mode of antinociceptive and toxic action of alkaloids of Aconitum spec

Extracts of the plant Aconitum spec. are used in traditional Chinese medicine predominantly as anti-inflammatory and analgesic agents, the latter allegedly equally potent as morphine but without any habit-forming potential. As the only pharmacologically active compounds, the C19 diterpenoid alkaloid aconitine, and some of its derivatives, have been proven to be antinociceptive in different analgesic assays, but the mode of action is unknown. To elucidate the mode of action, ten aconitine-like derivatives were investigated with respect to their affinity for voltage-dependent Na+ channels, the action on synaptosomal Na+ and Ca2+ homoeostasis and their antinociceptive, arrhythmogenic and acute toxic properties. Since aconitine is known to bind to site II of Na+ channels, we determined the affinity of the aconitine-like derivatives in vitro to synaptosomal membranes by the [3H]-batrachotoxinin-binding assay and their properties on intrasynaptosomal concentrations of free Na+ and Ca2+ ([Na+]i and [Ca2+]i), both the latter determined fluorometrically with SBFI and Fura-2 respectively. Furthermore, the alkaloids' arrhythmogenic potential was investigated in guinea-pig isolated atria and the antinociceptive action on formalin-induced hyperalgesia and the acute toxic action estimated in mice. The results show that the alkaloids could be divided into at least three groups. The first is characterized by a high affinity to the site II of Na+ channels (Ki about 1.2 microM), the ability to enhance [Na+]i and [Ca2+]i (EC50 about 3 microM), a strong arrhythmogenic action that starts at about 30 nM, an antinociceptive effect (ED50 about 0.06 mg/kg) and high acute toxicity (LD50 values about 0.15 mg/kg). To this group belong aconitine, 3-acetylaconitine and hypaconitine. The second group, with lappaconitine as the only member, has an affinity to Na+ channels an order of magnitude lower (Ki = 11.5 microM), less acute toxicity (LD50 about 5 mg/kg), and a two orders of magnitude lower antinociceptive action (ED50 about 2.8 mg/kg) and lower cardiotoxicity (bradycardia observed at 3 microM). Additionally, lappaconitine suppresses the increase in [Ca2+]i of aconitine-stimulated synaptosomes and increases the excitation threshold of left atria, indicating an inhibition of Na+ channels. The other derivatives, i.e. delcorine, desoxydelcorine, karakoline, lappaconidine, lappaconine and lycoctonine, belong to the third group, which has hardly any effects. They have a low affinity to Na+ channels with Ki values in the millimolar range, show no effect on synaptosomal [Na+]i and [Ca2+]i, no arrhythmogenic potential up to 100 microM, no antinociceptive activity and low toxicity with LD50 values greater than 50 mg/kg. For the investigated alkaloids we suggest two different antinociceptive-like modes of action. Aconitine, hypaconitine and 3-acetylaconitine may induce a block of neuronal conduction by a permanent cell depolarisation, whereas lappaconitine might act like local anaesthetics. However, because of the low LD50/ED30 quotients of 2-6, the antinociceptive-like action of the Aconitum alkaloids seems to reflect severe intoxication rather than a specific antinociceptive action. The structure/activity relationship shows that alkaloids that activate or block Na+ channels have a benzoyl ester side chain in the C-14 or C-4 positions respectively, whereas the other compounds lack this group.

Aconitum sp. alkaloids: the modulation of voltage-dependent Na+ channels, toxicity and antinociceptive properties

Alkaloids from Aconitum sp., used as analgesics in traditional Chinese medicine, were investigated to elucidate their antinociceptive and toxic properties considering: (1) binding to Na+ channel epitope site 2, (2) alterations in synaptosomal Na+ and Ca2+ concentration ([Na+]i, [Ca2+]i), (3) arrhythmogenic action of isolated atria, (4) antinociceptive and (5) acute toxic action in mice. The study revealed a high affinity group (Ki 1 microM) and a low affinity group (Ki 10 microM) of alkaloids binding to site 2. The compounds of the high affinity group induce an increase in synaptosomal [Na+]i and [Ca2+]i (EC50 3 microM), are antinociceptive (ED50, 25 microg/kg), provoke tachyarrhythmia and are highly toxic (LD50 70 microg/kg), whereas low affinity alkaloids reduce [Ca2+]i, induce bradycardia and are less antinociceptive (ED50 20 mg/kg) and less toxic (LD50 30 mg/kg). These results suggest that the alkaloids can be grouped in Na+ channel activating and blocking compounds, but none of the alkaloids seem to be suitable as analgesics because of the low LD50/ED50 values.

Development of the Abbott AxSYM Free PSA assay: performance characteristics and preliminary clinical evaluation

The AxSYM Free PSA assay was demonstrated to have good analytical sensitivity and reproducibility. The F/T ratio determinations for 385 men tested during the Prostate Awareness Week who had biopsies due to an elevated total PSA value and/or a suspicious DRE demonstrated that the percentage of free PSA was lower in patients found to have prostate cancer than those that were biopsy negative for the overall group and for all patient categories examined. The optimal strategy for combining PSA values, F/T ratios, DRE and other clinical and diagnostic parameters to improve the early detection of prostate cancer requires additional clinical studies.

Anticonvulsive action of (+/-)-kavain estimated from its properties on stimulated synaptosomes and Na+ channel receptor sites

Kava pyrones are constituents of the intoxicating pepper (Piper methysticum Forst), which has been shown to be anticonvulsive. The question of how the excitability of neurons is affected was investigated by determining the interaction of (+/-)-kavain with epitopes (site 1, site 2) of voltage-dependent Na+ channels and the action of (+/-)-kavain on 4-aminopyridine-stimulated synaptosomes as model of repetitive firing neurons. [3H]Saxitoxin and [3H]batrachotoxin were used for radioligand-binding assays performed with synaptosomal membranes. Gultamate released from 4-aminopyridine-stimulated cerebrocortical synaptosomes and the cytosolic concentrations of Na+ and Ca2+ ([Na+]i, [Ca+]i) were detected fluorometrically by using an enzyme-linked assay, sodium-binding benzofuranisophthalate (SBFI) and Fura-2, respectively. (+/-)-Kavain failed to compete with [3H]saxitoxin up to 400 mumol/l but dose-dependently suppressed binding of [3H]batrachotoxin with an IC50 value of 88 mumol/l (Ki = 72 mumol/l) although displacement of [3H]batrachotoxin was restricted to 33% of control at 400 mumol/l (+/-)-kavain. In stimulated synaptosomes, 5 mmol/l 4-aminopyridine provoked an increase in [Na+]i and [Ca2+]i by 9 mmol/l Na+ and 235 nmol/l Ca2+. Comparable to the reduction in [3H]batrachotoxin binding, 400 mumol/l (+/-)-kavain suppressed the increase in [Na+]i and [Ca2+]i to 38 and 29% of control, respectively. Consistent with the increase in [Na+]i and [Ca2+]i, 5 mmol/l 4-aminopyridine provoked glutamate release (rate: 38 pmol/s*mg protein) which was dose-dependently diminished to 60% of control by 400 mumol/l (+/-)-kavain. KCl depolarization (40 mmol/l) provoked an increase in [Ca2+]i and glutamate release almost identical to the responses elicited by 4-aminopyridine but 400 mumol/l (+/-)-kavain suppressed only the rate of glutamate release by 9% of control. The data suggest an interaction of (+/-)-kavain with voltage-dependent Na+ and Ca2+ channels, thereby suppressing the 4-aminopyridine-induced increase in [Na+]i, [Ca2+]i and the release of endogenous glutamate.