Ionoacoustic characterization of the proton Bragg peak with submillimeter accuracy

PURPOSE

Range verification in ion beam therapy relies to date on nuclear imaging techniques which require complex and costly detector systems. A different approach is the detection of thermoacoustic signals that are generated due to localized energy loss of ion beams in tissue (ionoacoustics). Aim of this work was to study experimentally the achievable position resolution of ionoacoustics under idealized conditions using high frequency ultrasonic transducers and a specifically selected probing beam.

METHODS

A water phantom was irradiated by a pulsed 20 MeV proton beam with varying pulse intensity and length. The acoustic signal of single proton pulses was measured by different PZT-based ultrasound detectors (3.5 and 10 MHz central frequencies). The proton dose distribution in water was calculated by Geant4 and used as input for simulation of the generated acoustic wave by the matlab toolbox k-WAVE.

RESULTS

In measurements from this study, a clear signal of the Bragg peak was observed for an energy deposition as low as 10(12) eV. The signal amplitude showed a linear increase with particle number per pulse and thus, dose. Bragg peak position measurements were reproducible within ±30 μm and agreed with Geant4 simulations to better than 100 μm. The ionoacoustic signal pattern allowed for a detailed analysis of the Bragg peak and could be well reproduced by k-WAVE simulations.

CONCLUSIONS

The authors have studied the ionoacoustic signal of the Bragg peak in experiments using a 20 MeV proton beam with its correspondingly localized energy deposition, demonstrating submillimeter position resolution and providing a deep insight in the correlation between the acoustic signal and Bragg peak shape. These results, together with earlier experiments and new simulations (including the results in this study) at higher energies, suggest ionoacoustics as a technique for range verification in particle therapy at locations, where the tumor can be localized by ultrasound imaging. This acoustic range verification approach could offer the possibility of combining anatomical ultrasound and Bragg peak imaging, but further studies are required for translation of these findings to clinical application.

Intestinal immunopathology is associated with decreased CD73-generated adenosine during lethal infection

The ectonucleotidases CD39 and CD73 sequentially degrade the extracellular ATP pool and release immunosuppressive adenosine, thereby regulating inflammatory responses. This control is likely to be critical in the gastrointestinal tract where high levels of ATP are released in particular by commensal bacteria. The aim of this study was therefore to evaluate the involvement of the adenosinergic regulation in the intestine of mice in steady-state conditions and on acute infection with Toxoplasma gondii. We show that both conventional (Tconv) and regulatory (Treg) CD4(+) T lymphocytes express CD39 and CD73 in the intestine of naive mice. CD73 expression was downregulated during acute infection with T. gondii, leading to impaired capacity to produce adenosine. Interestingly, the expression of adenosine receptors was maintained and treatment with receptor agonists limited immunopathology and dysbiosis, suggesting that the activation of adenosine receptors may constitute an efficient approach to control intestinal inflammation associated with decreased ectonucleotidase expression.

Propranolol and newer antihypertensive drugs in the management of hypertension

Among the newer antihypertensive agents are the beta-blocking drugs, such as propranolol. These agents are useful as second-step drugs to be used if diuretic therapy alone is not effective. In mild to moderately severe hypertension, propranolol, in does of up to 480 mg/day in combination with a thiazide diuretic, has been found to be effective in over 80% of patients on long-term therapy. This degree of response is essentially similar to that noted with a combination of reserpine and a diuretic agent. Although some observers believe that propranolol produces many fewer side effects than the other step 2 drugs (reserpine and alpha-methyldopa), there are some patients who do experience restlessness, insomnia, and depression. Clonidine may be substituted for another step 2 drug, is of moderate potency, but may not be tolerated by a large number of patients because of the severe dry mouth and drowsiness that it produces. Prazosin appears to be a suitable substitute for hydralazine as an effective vasodialator if thiazides plus propranolol or thiazides plus reserpine or alpha-methyldopa are not effective. In some instances, it many be an acceptable second-step drug because of its alpha-adrenoreceptor-blocking properties. The angiotensin II competitive inhibitors or converting enzyme inhibitors may in the future have some place in the management of hypertension.

Peri- and postinterventional antithrombotic therapy in TAVI. Do we need antiplatelet therapy?

Interventional treatment of aortic valve stenosis by transcatheter aortic valve replacement (TAVR) has become routine practice in elderly and high risk patients in recent years. Similar to other vascular interventional or surgical procedures TAVR carries thrombotic risks such as stroke, myocardial infarction or systemic embolism as well as peri-procedural bleeding risks. These risks comprise the access site, the type of prosthesis, and the individual risk profile of the patient. Not only during the peri-procedural period but also during longterm follow-up the current target population for TAVR procedures carries a high risk for thrombotic events in particular if atrial fibrillation is present. On the other hand side the bleeding risk is also increased in these patients. Thus, to provide the optimal strategy of antithrombotic therapy during and after TAVR remains a clinical challenge.

Electrochemical and physicochemical properties of small phosphonium cation ionic liquid electrolytes with high lithium salt content

A novel phosphonium ionic liquid as potential candidate for lithium battery electrolytes.

[Recommendations for management of dyslipidemia in 2014]

Benefit of statin treatment is well established for secondary prevention. For primary prevention, good data exist to support use of statins in high-risk groups. Less data are available for intermediate risk group and very few patients at low risk have been included in clinical trials. In this context, an individual approach based on a risk stratification using PROCAM score adjusted for Switzerland is recommended. Lifestyle measures should be tried first. We also discuss the new American guidelines and their related controversies. Secondary causes and familiar forms of dyslipidemias, for which a risk assessment cannot be performed using risk scores (first cardiovascular event between age 20 and 60), should not be overlooked.

Effect of a mixture of bovine milk oligosaccharides, Lactobacillus rhamnosus NCC4007 and long-chain polyunsaturated fatty acids on catch-up growth of intra-uterine growth-restricted rats

AIM

To investigate the effect of a nutritional mixture (bovine milk oligosaccharides, Lactobacillus rhamnosus NCC4007, arachidonic and docosahexaenoic acid) on growth of intrauterine growth-restricted (IUGR) rats.

METHODS

IUGR was induced by maternal food restriction. The offspring (males and females) were assigned to: REF (non-IUGR, no mixture), IUGRc (IUGR, no mixture), or IUGRmx (IUGR, mixture). The mixture was given from day 7 to day 58, when tissues and plasma from half of the animals were collected for hormones, metabolites and microarray analysis. The rest received a high-fat diet (HFD) until day 100. Glucose tolerance was measured at 56 and 98 days, and body fat content at 21, 52 and 97 days.

RESULTS

IUGRmx had the greatest growth during lactation, but from day 22 to day 54, both IUGR groups gained less body weight than the REF (P < 0.05). In the short-term (58 days), IUGRmx tended to be longer (P = 0.06) and had less body fat (P = 0.03) than IUGRc. These differences were not seen after HFD. Microarray analysis of hepatic mRNA expression at 58 and 100 days revealed a gender-dependent treatment effect, and expression of genes related to lipid metabolism was the most affected. Twelve of these genes were selected for studying differences in DNA methylation in the promoter region, for some, we observed age- and gender-related differences but none because of treatment.

CONCLUSION

The nutritional intervention promoted catch-up growth and normalized excessive adiposity in IUGR animals at short-term. The benefits did not extend after a period of HFD. IUGR and early diet had gender-dependent effects on hepatic gene expression.

Radiofrequency ablation technique in the treatment of liver tumours: review and future issues

Thermal ablation is increasingly being used for treatment of liver tumours. Among the techniques of thermal ablation, radiofrequency ablation (RF) is undoubtedly being used most frequently because of its advantages, such as morbidity and mortality rates, effective tumour ablation, as well as being less time-consuming. This paper presents the state of the art of RF ablation technique. This includes the theoretical development, experimental study and clinical application of the radiofrequency ablation technique. First, it introduces the principle of this technique. Second, it shows the development of this technique and valuable achievements. These achievements include the device, strategy of operation and extension to other diseases. Third, it concludes future issues to be addressed in order to further advance this technique.

Thrombin receptor antagonism in antiplatelet therapy

Activated platelets play a crucial role in the pathogenesis of atherothrombotic disease and its complications. Even under treatment of antiplatelet drugs, such as acetylsalicylic acid and P2Y12 antagonists, morbidity and mortality rates of thromboembolic complications remain high. Hence, the therapeutic inhibition of protease-activated receptor (PAR)-1, which is activated by thrombin, is a novel promising approach in antiplatelet therapy. Recent data suggest that PAR-1 is mainly involved in pathological thrombus formation, but not in physiological hemostasis. Therefore, PAR-1 inhibition offers the possibility to reduce atherothrombotic events without increasing bleeding risk. So far, two emerging PAR-1 antagonists have been tested in clinical trials: vorapaxar (SCH530349; Merck & Co., Whitehouse Station, NJ, USA) and atopaxar (E5555; Eisai, Tokyo, Japan). Although in TRA-CER vorapaxar showed an unfavorable profile for patients with acute coronary syndrome in addition to standard therapy, it revealed promising results for patients with prior myocardial infarction in TRA 2P-TIMI50. Depending on the status of clinical approval, vorapaxar might be an option for patients with peripheral arterial disease to reduce limb ischemia. The second PAR-I antagonist, atopaxar, tended towards reducing major cardiovascular adverse events in acute coronary syndrome patients in a phase II trial. However, although statistically not significant, bleeding events were numerically increased in atopaxar-treated patients compared with placebo. Furthermore, liver enzymes were elevated and the relative corrected QT interval was prolonged in atopaxar-treated patients. Currently, the development of atopaxar by Eisai is discontinued. The future of this novel class of antithrombotic drugs will depend on the identification of patient groups in which the risk–benefit ratio is favorable.

Microsupport with Two-Dimensional Geometry (2D-MS)

CHO-K1 and VERO cells have been grown on MicroHextrade mark, a polystyrene-based microsupport with two-dimensional geometry and the consistency of their growth kinetics were established. These cells have been detached by exposure to buffered ethylenediaminetetraacetic acid (EDTA) followed by controlled mechanical shear to yield well-isolated cells suspended in EDTA. Neutralisation of the EDTA followed by restoration of the chemical composition of the growth medium causes detached CHO-K1 cells to display unaltered growth kinetics.

[Rivaroxaban in the prevention and treatment of thromboembolic disorders]

Rivaroxaban (Xarelto(®)) is a new anticoagulant for the prevention and treatment of thromboembolic disorders. Rivaroxaban inhibits coagulation factor Xa directly, has high oral bioavailability, shows low propensity for drug-drug interactions and requires no routine coagulation monitoring. In patients undergoing elective knee or hip replacement surgery rivaroxaban (10 mg/d) is highly effective to prevent venous thromboembolism. In patients with non-valvular atrial fibrillation rivaroxaban (20 mg/d) has been approved to prevent stroke or systemic embolism. The favourable benefit-risk profile of rivaroxaban in the treatment of deep vein thrombosis (DVT) was shown in EINSTEIN-DVT and led to its clinical approval (twice daily 15 mg for 3 weeks, followed by 20 mg/d). Based on ATLAS-ACS-TIMI-51 which has shown that rivaroxaban (2.5 mg twice daily) reduced thrombotic cardiovascular events and mortality in patients with a recent acute coronary syndrome, the approval of low dose rivaroxaban has been submitted for this indication. Taken together, rivaroxaban may become an effective alternative to standard anticoagulants in the prevention and treatment of thromboembolic disorders.