Search

Purpose: Cardiac radioablation is a novel treatment option for patients with refractory ventricular tachycardia unsuitable for catheter ablation. The quality of treatment planning depends on dose specifications, platform capabilities, and experience of the treating staff. To harmonize the treatment planning, benchmarking of this process is necessary for multicenter clinical studies such as the RAdiosurgery for VENtricular TAchycardia trial., Methods and Materials: Planning computed tomography data and consensus structures from 3 patients were sent to 5 academic centers for independent plan development using a variety of platforms and techniques with the RAdiosurgery for VENtricular TAchycardia study protocol serving as guideline. Three-dimensional dose distributions and treatment plan details were collected and analyzed. In addition, an objective relative plan quality ranking system for ventricular tachycardia treatments was established., Results: For each case, 3 coplanar volumetric modulated arc (VMAT) plans for C-arm linear accelerators (LINAC) and 3 noncoplanar treatment plans for robotic arm LINAC were generated. All plans were suitable for clinical applications with minor deviations from study guidelines in most centers. Eleven of 18 treatment plans showed maximal one minor deviation each for target and cardiac substructures. However, dose-volume histograms showed substantial differences: in one case, the planning target volume ≥30 Gy ranged from 0.0% to 79.9% and the ramus interventricularis anterior V 14Gy ranged from 4.0% to 45.4%. Overall, the VMAT plans had steeper dose gradients in the high-dose region, while the plans for the robotic arm LINAC had smaller low-dose regions. Thereby, VMAT plans required only about half as many monitor units, resulting in shorter delivery times, possibly an important factor in treatment outcome., Conclusions: Cardiac radioablation is feasible with robotic arm and C-arm LINAC systems with comparable plan quality. Although cross-center training and best practice guidelines have been provided, further recommendations, especially for cardiac substructures, and ranking of dose guidelines will be helpful to optimize cardiac radioablation outcomes., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background/aim: Many patients with head-and-neck cancers receive radiotherapy. Treatment planning can be very complex in case of dental fillings or implants that cause metal artefacts. Verification of dose distributions may be performed using specific phantoms. This study aimed to develop a 3D-printed phantom that can be produced easily and cost-effectively., Patients and Methods: The phantom was designed to allow fast adaption to a patient's individual situation with a particular focus on metal artefacts due to dental fillings. Bone and soft-tissue shells were 3D-printed and filled with tissue-equivalent materials., Results: Attenuation properties of the tissue-equivalent structures in the phantom corresponded well to the structures of real human anatomy. In magnetic resonance (MR)-imaging, useful signals of the materials in the phantom were obtained., Conclusion: The phantom met the requirements including equivalence with human tissues and can be useful for highly individual treatment planning in precision-radiotherapy of head-and-neck cancers. It can be also used for scientific issues related to MR-imaging., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Purpose: Although the metric precision of robotic stereotactic body radiation therapy in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase-related residual tracking errors., Methods and Materials: In 24 patients (28 liver metastases) treated with the CyberKnife, we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into 10 breathing phases. The average breathing phase errors were used to shift and rotate the clinical tumor volume (CTV) and planning target volume (PTV) for each phase to calculate a pseudo 4-dimensional error dose distribution for comparison with the original planned dose distribution., Results: The median systematic directional correlation, prediction, and absolute aggregate rotation errors were 0.3 mm (range, 0.1-1.3 mm), 0.01 mm (range, 0.00-0.05 mm), and 1.5° (range, 0.4°-2.7°), respectively. Dosimetrically, 44%, 81%, and 92% of all voxels differed by less than 1%, 3%, and 5% of the planned local dose, respectively. The median coverage reduction for the PTV was 1.1% (range in coverage difference, -7.8% to +0.8%), significantly depending on correlation (P=.026) and rotational (P=.005) error. With a 3-mm PTV margin, the median coverage change for the CTV was 0.0% (range, -1.0% to +5.4%), not significantly depending on any investigated parameter. In 42% of patients, the 3-mm margin did not fully compensate for the residual tracking errors, resulting in a CTV coverage reduction of 0.1% to 1.0%., Conclusions: For liver tumors treated with robotic stereotactic body radiation therapy, a safety margin of 3 mm is not always sufficient to cover all residual tracking errors. Dosimetrically, this translates into only small CTV coverage reductions., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Structural relaxation phenomena in binary and multicomponent lithium silicate glasses were studied upon irradiation with femtosecond (fs) laser pulses (800 nm central wavelength, 130 fs pulse duration) and subsequent thermal annealing experiments. Depending on the annealing temperature, micro-Raman spectroscopy analyses evidenced different relaxation behaviours, associated to bridging and non-bridging oxygen structures present in the glass network. The results indicate that the mobility of lithium ions is an important factor during the glass modification with fs-laser pulses. Quantitative phase contrast imaging (spatial light interference microscopy) revealed that these fs-laser induced structural modifications are closely related to local changes in the refractive index of the material. The results establish a promising strategy for tailoring fs-laser sensitivity of glasses through structural mobility.

The cyanobacterium Acaryochloris marina is unique because it mainly contains Chlorophyll d (Chl d) in the core complexes of PS I and PS II instead of the usually dominant Chl a. Furthermore, its light harvesting system has a structure also different from other cyanobacteria. It has both, a membrane-internal chlorophyll containing antenna and a membrane-external phycobiliprotein (PBP) complex. The first one binds Chl d and is structurally analogous to CP43. The latter one has a rod-like structure consisting of three phycocyanin (PC) homohexamers and one heterohexamer containing PC and allophycocyanin (APC). In this paper, we give an overview on the investigations of excitation energy transfer (EET) in this PBP-light-harvesting system and of charge separation in the photosystem II (PS II) reaction center of A. marina performed at the Technische Universität Berlin. Due to the unique structure of the PBP antenna in A. marina, this EET occurs on a much shorter overall time scale than in other cyanobacteria. We also briefly discuss the question of the pigment composition in the reaction center (RC) of PS II and the nature of the primary donor of the PS II RC., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

Fifteen out of 24 risk neonates from the premature baby ward (= 63%) and 36 of 79 healthy neonates from the infant nursery (= 46%) at a Zürich hospital were infected within a period of 29 days during a nosocomial epidemic human rotavirus (HRV) outbreak. Forty-two out of 51 of all HRV-infected babies (=82%) manifested clinical symptoms, but these could not all be attributed to an HRV infection. On average, rotavirus could be detected in infected risk neonates five days after their admission to the premature baby ward. Eleven of the 15 risk neonates were infected within 10 days after the admission of the index case. Immediately after detection of the epidemic process, specific detailed countermeasures were instituted, including hand protection and hand disinfection, individual nursing set and cohorting of already infected babies. Early institution of such measures and information of all persons responsible for treatment and care of the babies concerned are crucial for success.

The effectiveness of local and parenteral antibiotic prophylaxis in infections of aortic dacron grafts was tested in animal experiments. In 20 foxhounds Dacron-interpositions, 4 cms in length, were inoculated with 50 million Staph aureus bacteria and then treated in 4 different ways: Nr. 1-5 no antibiotic treatment. Nr. 6-10 local antibiotic (Nebacetin, R) treatment. Nr 11-15 parenteral treatment with Gramaxin (R) i.m. Nr. 16-20 combined Nebacetin (R) and Gramaxin (R) treatment. The untreated dogs developed infection of laparotomy wounds, peritoneum udn prosthesis. Nebacetin gave improved results, whereas Gramaxin led to complete eradication of the infection. It is concluded, that antibiotic prophylaxis should be applied in vascular surgery, whenever alloplastic, homologous or autologous implants are used.

Bacteriological testing in tracheotomized patients has shown that infection can be avoided when only sterilized water is used for post-surgical humidification and is disinfected at least every two days. In so doing, water condensation can be avoided by the use of concomitant tube heating. Conclusions indicate that humidifers which utilize water evaporation are more useful in patient care than ultra-sonic nebulizers.

During a nine-month period in 1986, we observed five ornithine decarboxylase-negative isolates of Serratia marcescens from four different patients. All isolates were identical in more than 50 biochemical parameters. Four isolates from three hospitalized patients were essentially identical in their susceptibility patterns to 12 antimicrobial agents. Analysis of 35-S-methionine labeled whole cell proteins by SDS-PAGE with the AMBIS system (Automated Microbiology System Inc., San Diego, CA) suggested that only three of these isolates were identical while the fourth hospital strain was more closely related to the isolate of a patient with no contact to the hospital. These results were confirmed by bacteriocin- and serotyping. We conclude that analysis of these protein patterns--which does not require special reagents - was an adequate method for typing S. marcescens.

Ceftriaxon (Ro 13-9904) is a new cephalosporin, whose structure resembles cefotaxime. This study compares the minimal inhibitory concentrations (MIC-s) of Ceftriaxon, cefoperazone, cefotaxime, lamoxactam and gentamicin against 622 isolates of various Enterobacteriaceae, non-fermenters and Aeromonas hydrophila. Furthermore the minimal bactericidal concentrations (MBC-s) were determined for some organism; additionally destruction of beta-lactamantibiotics in the presence of beta-lactamases was studied by a bioassay technique. The in vitro activity of Ceftriaxon against gramnegative bacteria was found very similar to that of cefotaxime. The susceptibility of Enterobacter sp. to the three cephalosporines was exceeded by lamoxactam while cefoperazone was the most active beta-lactam-antibiotic against Pseudomonas. Lactamases, which inactivated cefotaxime also destroyed Ceftriaxon in a greater extend. No hydrolysis of lamoxactam and cefoperazone occurred by nearly all bacterial extracts tested.

In this paper the application of intravital microkymography on studies of the microcirculation of the hamster cheek pouch is presented. Flow velocity reduction which is one of the characteristic initial alterations in small blood vessels after injection of endotoxin is recorded in a direct way by the strip microkymography. The method of the recording system is described and some examples of the effects of endotoxin as well as of serotonin, one of the mediators of endotoxin, are given. The advantage of microkymography in quantitative and functional studies of endotoxic actions, e.g. flow velocity decreases and vessel diameter changes, is discussed.

The diagnosis of obligately aerobic Gram-negative rods in the clinical laboratory may encounter difficulties since media used for Enterobacteriacae are only partially usable for the diagnosis of this group of bacteria (Psuedomonas, Xanthomonas, Alcaligenes, Achromobacter, Brucella, Bordetella, Flavobacterium, Moraxella, Acinetobacter, and some still unnamed taxa). We have developed a diagnostic scheme, based on recent publications in the field and representing an extension of earlier tables from this and other laboratories, which attempts to classify a maximal number of obligately aerobic Gram-negative rods with a minimal number of tests. The scheme, employed on 4051 strains, used blood agar and MacConkey Agar as isolation media. Growth characteristics on these media and microscopic morphology may be of help, but only the type of growth on Triple Sugar Iron (or Kligler's) Agar is characteristic for the group as a whole (no growth in the butt, alkalinization or no pH change on the slant). A primary identification series employs tests for oxidase (Kovacs), oxidation of glucose and xylose (in OF medium), deoxyribonuclease and indole (in DNase Test Agar with Methyl Green), nitrate reduction (in Indole Nitrite Medium), motility (hanging drop), and fluorescein production (on Flo Agar). Results of Kirby-Bauer antimicrobial sensitivity testing serve as additional (colistin) or confirmatory criteria. Incubation is at 30 degrees C for 24-48 hrs. If a diagnosis is not possible than, a secondary series, including tests for lysine decarboxylase (tablets), 4 hr urease, esculin hydrolysis, growth at 42 C and on SS Agar, gelatin liquefaction, and flagellar staining may have to be used, and read after 4-24 hrs at 30 degrees C. Five tables, drawn up according to oxidase, glucose, and xylose reactions, serve to identify the species or taxa. Biotypes cannot be differentiated. The scheme will need updating as more knowledge of these bacteria will become available.