iMPI: portable human-sized magnetic particle imaging scanner for real-time endovascular interventions.

Minimally invasive endovascular interventions have become an important tool for the treatment of cardiovascular diseases such as ischemic heart disease, peripheral artery disease, and stroke. X-ray fluoroscopy and digital subtraction angiography are used to precisely guide these procedures, but they are associated with radiation exposure for patients and clinical staff. Magnetic Particle Imaging (MPI) is an emerging imaging technology using time-varying magnetic fields combined with magnetic nanoparticle tracers for fast and highly sensitive imaging. In recent years, basic experiments have shown that MPI has great potential for cardiovascular applications. However, commercially available MPI scanners were too large and expensive and had a small field of view (FOV) designed for rodents, which limited further translational research. The first human-sized MPI scanner designed specifically for brain imaging showed promising results but had limitations in gradient strength, acquisition time and portability. Here, we present a portable interventional MPI (iMPI) system dedicated for real-time endovascular interventions free of ionizing radiation. It uses a novel field generator approach with a very large FOV and an application-oriented open design enabling hybrid approaches with conventional X-ray-based angiography. The feasibility of a real-time iMPI-guided percutaneous transluminal angioplasty (PTA) is shown in a realistic dynamic human-sized leg model.

[Perioperative anesthesia management of extended partial liver resection. Pathophysiology of hepatic diseases and functional signs of hepatic failure]. / Perioperatives anästhesiologisches Management bei ausgedehnten Leberteilresektionen. Pathophysiologie der Lebererkrankungen und funktionelle Zeichen des Leberversagens.

The importance of partial liver resection as a therapeutic option to cure hepatic tumors has increased over the last decades. This has been influenced on the one hand by advances in surgical and anesthetic management resulting in a reduced mortality after surgery and on the other hand by an increased incidence of hepatocellular carcinoma. Nowadays, partial resection of the liver is performed safely and as a routine operation in specialized centers. This article describes the pathophysiological changes secondary to liver failure and assesses the perioperative management of patients undergoing partial or extended liver resection. It looks in detail at the preoperative assessment, the intraoperative anesthetic management including fluid management and techniques to reduce blood loss as well as postoperative analgesia and intensive care therapy.

Magnetic particle imaging for artifact-free imaging of intracranial flow diverter stents: A phantom study.

PURPOSE: Magnetic Particle Imaging (MPI) is a new, background- and radiation-free tomographic imaging method that enables near real-time imaging of superparamagnetic iron-oxide nanoparticles (SPIONs) with high temporal and spatial resolution. This phantom study aims to investigate the potential of MPI for visualization of the stent lumen in intracranial flow diverters (FD). METHODS: Nitinol FD of different dimensions (outer diameter: 3.5 mm, 4.0 mm, 5.5 mm; total length: 22-40 mm) were scanned in vascular phantoms in a custom-built MPI scanner (in-plane resolution: ~ 2 mm, field of view: 65 mm length, 29 mm diameter). Phantoms were filled with diluted (1:50) SPION tracer agent Ferucarbotran (10 µmol (Fe)/ml; NaCL). Each phantom was measured in 32 different projections (overall acquisition time per image: 3200 ms, 5averages). After image reconstruction from raw data, two radiologists assessed image quality using a 5-point Likert scale. The signal intensity profile was measured using a semi-automatic evaluation tool. RESULTS: MPI visualized the lumen of all FD without relevant differences between the stented vessel phantom and the reference phantom. At 3.5 mm image quality was slightly inferior to the larger diameters. The FD themselves neither generated an MPI signal nor did they lead to relevant imaging artifacts. Ratings of both radiologists showed no significant difference, interrater reliability was good (ICC 0.84). A quantitative evaluation of the signal intensity profile did not reveal any significant differences (p > 0.05) either. CONCLUSION: MPI visualizes the lumen of nitinol FD stents in vessel phantoms without relevant stent-induced artifacts.

Rapid, high-yield production in plants of individualized idiotype vaccines for non-Hodgkin's lymphoma.

BACKGROUND: Animal and clinical studies with plant-produced single-chain variable fragment lymphoma vaccines have demonstrated specific immunogenicity and safety. However, the expression levels of such fragments were highly variable and required complex engineering of the linkers. Moreover, the downstream processing could not be built around standard methods like protein A affinity capture. DESIGN: We report a novel vaccine manufacturing process, magnifection, devoid of the above-mentioned shortcomings and allowing consistent and efficient expression in plants of whole immunoglobulins (Igs). RESULTS: Full idiotype (Id)-containing IgG molecules of 20 lymphoma patients and 2 mouse lymphoma models were expressed at levels between 0.5 and 4.8 g/kg of leaf biomass. Protein A affinity capture purification yielded antigens of pharmaceutical purity. Several patient Igs produced in plants showed specific cross-reactivity with sera derived from the same patients immunized with hybridoma-produced Id vaccine. Mice vaccinated with plant- or hybridoma-produced Igs showed comparable protection levels in tumor challenge studies. CONCLUSIONS: This manufacturing process is reliable and robust, the manufacturing time from biopsy to vaccine is <12 weeks and the expression and purification of antigens require only 2 weeks. The process is also broadly applicable for manufacturing monoclonal antibodies in plants, providing 50- to 1000-fold higher yields than alternative plant expression methods.

Magnetic Particle Imaging for Quantification of Vascular Stenoses: A Phantom Study.

Magnetic particle imaging (MPI) is a promising new tomographic imaging method to detect the spatial distribution of superparamagnetic iron-oxide nanoparticles (SPIOs). The aim of this paper was to investigate the potential of MPI to quantify artificial stenoses in vessel phantoms. Custom-made stenosis phantoms (length 40 mm; inner diameter 8 mm) with different degrees of stenosis (0%, 25%, 50%, 75%, and 100%) were scanned in a custom-built MPI scanner (in-plane resolution: ~1-1.5 mm and field of view: 65 29 29 mm3). Phantoms were filled with diluted Feru-carbotran [SPIO agent, 5 mmol (Fe)/l]. Each measurement (overall acquisition time: 20 ms per image, 400 averages) was repeated ten times to assess reproducibility. The MPI signal was used for semi-automatic stenosis quantification. Two stenosis evaluation approaches were compared based on the signal intensity profile alongside the stenosis phantoms. Using a novel multi-step image evaluation approach, MPI allowed for accurate quantification of different stenosis grades. While low grade stenoses were slightly over-estimated, high grade stenoses were slightly underestimated. In particular, the 0%, 25%, and 50% stenosis phantoms revealed a 6.2% ± 0.8, 25.7% ± 1.0, and 48.0% ± 1.5 stenosis, respectively. The higher grade 75% stenosis phantom revealed a 73.3% ± 2.8 and the 100% stenosis phantom a 95.8%± 1.9 stenosis. MPI accurately visualized and quantified different stenosis grades in vessel phantoms with high reproducibility demonstrating its great potential for fast and radiation-free preclinical cardiovascular imaging.

Biosynthesis of terpenoids: 1-deoxy-D-xylulose-5-phosphate reductoisomerase from Escherichia coli is a class B dehydrogenase.

1-Deoxy-D-xylulose-5-phosphate is converted into 2-C-methyl-D-erythritol-4-phosphate by the catalytic action of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (Dxr protein) using NADPH as cofactor. The stereochemical features of this reaction were investigated in in vitro experiments with the recombinant Dxr protein of Escherichia coli using (4R)- or (4S)-[4-(2)H(1)]NADPH as coenzyme. The enzymatically formed 2-C-methyl-D-erythritol-4-phosphate was isolated and converted into 1,2:3,4-di-O-isopropylidene-2-C-methyl-D-erythritol; NMR spectroscopic investigation of this derivative indicated that only (4S)-[4-(2)H(1)]NADPH affords 2-C-methyl-D-erythritol-4-phosphate labelled exclusively in the H(Re) position of C-1. Stereospecific transfer of H(Si) from C-4 of the cofactor identifies the Dxr protein of E. coli as a class B dehydrogenase.

Biosynthesis of riboflavin in plants. The ribA gene of Arabidopsis thaliana specifies a bifunctional GTP cyclohydrolase II/3,4-dihydroxy-2-butanone 4-phosphate synthase.

A cDNA segment from Arabidopsis thaliana with similarity to the ribA gene of Bacillus subtilis was sequenced. A similar gene was cloned from tomato. The open reading frame of A. thaliana was fused to the malE gene of Escherichia coli and was expressed in a recombinant E. coli strain. The recombinant fusion protein was purified and shown to have GTP cyclohydrolase II activity as well as 3,4-dihydroxy-2-butanone 4-phosphate synthase activity. The cognate gene was amplified by polymerase chain reaction from chromosomal Arabidopsis DNA and was shown to contain six introns. Intron 4 is located in the region connecting the GTP cyclohydrolase II and 3,4-dihydroxy-2-butanone 4-phosphate synthase domain of the putative domains catalyzing the two reaction steps. By comparison with the bacterial ribA gene, the Arabidopsis gene contains an additional 5' element specifying about 120 amino acid residues. This segment contains numerous serine and threonine residues and does not show similarity with other known sequences. The N-terminal segment is not required for catalytic activity and is likely to serve as signal sequence for import into chloroplasts.

Psychological principles of burn wound pain in children. II: Treatment applications.

The pain involved in acute burn care can be excruciating and intractable. Even the best pharmacologic pain control efforts often fail to adequately control pain, especially procedure-related pain, in pediatric patients with burn injuries. Nonpharmacologic interventions have been found to be effective in reducing pain in both children and adults and can be extremely important adjuvants to standard pharmacologic analgesia in the burn care setting. In the first article in this series, we outlined psychological factors that influence the emotions, cognitions, and behaviors of children during wound care. Building on this theoretical framework, we now present a detailed discussion of the implementation of nonpharmacologic intervention strategies in the burn care setting. Because accurate measurement of discomfort is imperative for the development of interventions and for the evaluation of their efficacy, we begin with a brief review of pain measurement techniques. We follow this with suggestions for tailoring interventions to meet specific patient needs and conclude with a detailed and practical discussion of specific intervention techniques and the implementation of those techniques.

Psychological principles of burn wound pain in children. I: theoretical framework.

Burn injuries and the care of burn injuries are punishing experiences for hospitalized children. Pain, novelty, and altered reinforcement schedules elicit instinctive escape and avoidance behaviors that complicate wound care. An understanding of the psychological principles that underlie these complex, complicating behaviors paves the way for effective cognitive and behavioral interventions. In this first article of a two-part series, we use the principles of classical conditioning, operant conditioning, and control coping to describe the developmentally normal emergence of avoidance behaviors that are incompatible with burn wound care. Then, using brief case examples, we outline how classical conditioning transforms neutral stimuli into anxiety-producing, fearful stimuli, how operant behaviors are intentionally or unintentionally reinforced, and how the umbrella of reduced control in the novel hospital environment makes coping difficult for children. We conclude by discussing obstacles to effective application of cognitive and behavioral strategies for the enhancement of control and of compliance with wound care.

Sleep disturbance after burn injury.

This study describes sleep disturbance and related factors in a group of 74 patients at 1 week after discharge using a sleep problems questionnaire developed by the authors. Results indicated that a significant proportion of patients reported a problem with their sleep (73%). Several items were identified as highly prevalent, including frequent nighttime awakenings (87%), napping during the daytime (65%), sleeping alone (64%), experiencing pain during the night (62%), and difficulties with sleep onset (62%). Results suggest numerous possible interventions to improve patients' sleep quality. The usefulness of a more extensive questionnaire was also indicated.

Comparison of pain control medication in three age groups of elderly patients.

There are no published reports of burn pain management in the elderly population. To assess the range of requirement and use of opioids among elderly patients with burns of different age categories, a retrospective review of 89 consecutive admissions of patients over 55 years of age (January 1995 through July 1996) was conducted. Complete data were available on 44 patients with a burn mean total body surface area of 17.2%. Patient ages ranged from 55 to 92 years. Individuals were divided into three age categories: Group I (55 to 65) n = 20; Group II (66 to 75) n = 14; and Group III (76 to 92) n = 10. Use of commonly prescribed opioids for procedural pain and breakthrough pain were evaluated. We compared the opioid equivalents of medications prescribed versus the actual amount administered. Paired t tests comparing minimum amount of medication ordered with that given revealed Group I patients received significantly more procedural medication than the minimum prescribed (t = 3.88, p = 0.001), and that Group III patients were given significantly less as needed medication than the minimum prescribed (t = 2.58, p < 0.05).

Don't test, do sell: legal implications of inclusion and exclusion of women in clinical drug trials.

This article explores the historic underpinnings of the exclusion of women from clinical drug trials, identifies recent developments, and examines legal implications for women with epilepsy and for others. Distinguishing stakeholders and their interests may lead to policies that better serve all. Past and present statutory, regulatory, and judicial frameworks were reviewed, as well as legal, medical, and historical commentary. Traditionally, researchers and manufacturers have not tested particular drugs on women. Physicians and pharmacists routinely prescribe and sell these same medications regardless of gender. Only since 1993 have females been more likely to be included in clinical drug trial subject pools. The impact of past and future practices on health care provision and legal liability remains unknown. A policy of "Don't test, do sell" will not protect women with epilepsy or would-be defendants. At this time the most effective shields will involve procurement of informed consent as well as testing of both women and men. In the long run, tort, health care, and regulatory reform will best serve all interested persons. Inclusion of women in clinical drug trials has become a how question, not an if one.

Biosynthesis of riboflavin: studies on the mechanism of GTP cyclohydrolase II.

GTP cyclohydrolase II catalyzes the first committed reaction in the biosynthesis of the vitamin riboflavin. The recombinant enzyme from Escherichia coli is shown to produce 2,5-diamino-6-beta-ribosylamino-4(3H)-pyrimidinone 5'-phosphate and GMP at an approximate molar ratio of 10:1. The main product is subject to spontaneous isomerization affording the alpha-anomer. (18)O from solvent water is incorporated by the enzyme into the phosphate group of the 5-aminopyrimidine derivative as well as GMP. These data are consistent with the transient formation of a covalent phosphoguanosyl derivative of the enzyme. Subsequent ring opening of the covalently bound nucleotide followed by hydrolysis of the phosphodiester bond could then afford the pyrimidine type product. The hydrolysis of the phosphodiester bond without prior ring opening could afford GMP. The enzyme reaction is cooperative with a Hill coefficient of 1.3. Inhibition by pyrophosphate is competitive. Inhibition by orthophosphate is partially uncompetitive at low concentration and competitive at concentrations above 6 mm.

Efficient plastid transformation in tobacco using the aphA-6 gene and kanamycin selection.

Here we report on the development of a new dominant selection marker for plastid transformation in higher plants using the aminoglycoside phosphotransferase gene aphA-6 from Acinetobacter baumannii. Vectors containing chimeric aphA-6 gene constructs were introduced into the tobacco chloroplast using particle bombardment of alginate-embedded protoplast-derived micro colonies or polyethylene glycol (PEG)-mediated DNA uptake. Targeted insertion into the plastome was achieved via homologous recombination, and plastid transformants were recovered on the basis of their resistance to kanamycin. Variations in kanamycin resistance in transplastomic lines were observed depending on the 5' and 3' regulatory elements associated with the aphA-6 coding region. Transplastomic plants were fertile and showed maternal inheritance of the transplastome in the progeny.

Phosphorylation of 1-deoxy-D-xylulose by D-xylulokinase of Escherichia coli.

1-deoxy-D-xylulose 5-phosphate serves as a precursor for the biosynthesis of the vitamins thiamine and pyridoxal and for the formation of isopentenyl pyrophosphate and dimethylallyl pyrophosphate via the nonmevalonate pathway of terpenoid biosynthesis. Earlier studies had shown that Escherichia coli incorporates unphosphorylated 1-deoxy-D-xylulose into the terpenoid side chain of ubiquinones with high efficacy. We show that D-xylulokinase of E. coli (EC 2.7.1.17) catalyzes the phosphorylation of 1-deoxy-D-xylulose at the hydroxy group of C-5 at a rate of 1.6 micromol.mg min-1. This reaction constitutes a potential salvage pathway for the generation of 1-deoxy-D-xylulose 5-phosphate from exogenous or endogenous 1-deoxy-D-xylulose as starting material for the biosynthesis of terpenoids, thiamine and pyridoxal.

Biosynthesis of riboflavin.

The biosynthesis of one riboflavin molecule requires one molecule of GTP and two molecules of ribulose 5-phosphate. The imidazole ring of GTP is hydrolytically opened, yielding a 4,5-diaminopyrimidine that is converted to 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione by a sequence of deamination, side chain reduction, and dephosphorylation. Condensation of 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione with 3,4-dihydroxy-2-butanone 4-phosphate obtained from ribulose 5-phosphate affords 6,7-dimethyl-8-ribityllumazine. Dismutation of the lumazine derivative yields riboflavin and 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione, which is recycled in the biosynthetic pathway. Two reaction steps in the biosynthetic pathway catalyzed by 3,4-dihydroxy-2-butanone 4-phosphate synthase and riboflavin synthase are mechanistically very complex. The enzymes of the riboflavin pathway are potential targets for antibacterial agents.