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.

Abstract P6-11-14: Safety and effectiveness of sensor-controlled scalp cooling to prevent alopecia in primary breast cancer patients receiving neoadjuvant or adjuvant epirubicin, taxanes, or both

Background: Chemotherapy (Ctx)-induced alopecia (CIA), produces a deep psychological distress in many women involved. Sensor-controlled scalp cooling (SCSC) is now approved by the FDA due to both its effectiveness and safety to prevent CIA demonstrated in two randomized trials in patients (pts) with primary breast cancer (PBC). However, SCSC is still infrequently used in many countries due to physicians´ concerns regarding both its safety and feasibility, in particular regarding anthracycline-based Ctx [Nangia et al., 2017]. This retrospective analysis was initiated to obtain more detailed information on the effectiveness and safety of SCSC using the Paxman system (Paxman, Huddersfield, UK) in PBC pts exposed to CIA-inducing neoadjuvant (NACT) or adjuvant Ctx (ACT) based on epirubicin (E), taxanes (T), or both (ET) in the clinical routine. Methods: 79 pts who underwent SCSC alongside with Ctx for PBC from 2014-2017 were identified from our database: NACT, 41 (51.9%); ACT, 38 (48.1%); dose-dense (dd) Ctx, 56 (70.9%); non-dd Ctx 23 (29.1%); premenopausal, 44 (55.7%); postmenopausal, 35 (44.3%). The following Ctx regimens were used: E, 1 (1.3%); T, 23 (29.1%); ET, 55 (69.6%). Pts were subjected to SCSC during each Ctx cycle. CIA was quantified according to the Dean score (DS) determined 3 wks after the last Ctx cycle. Data were analyzed regarding feasibility indicated by the SCSC completion rate, quality of hair preservation (success: DS 0-2, failure: DS 3-4), reasons of SCSC discontinuation, and safety. Moreover, the following parameters were investigated in regard to the success of SCSC: menopausal status (pre- vs postpenopausal), NACT vs ACT, dd Ctx vs non-dd Ctx, E- or ET-based Ctx vs T-based Ctx. Results: 55 pts (69.6%) completed SCSC, with 36 (45.6%) experiencing complete hair preservation (DS 0), and 19 (22.8%) showing partial success (DS 1-2). 24 pts (30.4%) discontinued SCSC, with CIA being the main reason in 18 pts (22.8%). Headache or earache was reported in 2 pts (1.3%) each, and local discomfort in another 4 pts (5.1%). Side effects were all not severe and resolved quickly after cessation of SCSC. SCSC was equally effective in most analyzed subgroups. The relative risk (RR) to experience CIA was 1.11 (CI: 0.82-1.54) for post- vs premenopausal pts, 1.11 (CI: 0.83-1.53) for ACT vs NACT, and 0.99 (CI: 0.72-1.43) for dd Ctx vs non-dd Ctx. Pts receiving E or ET had a significantly higher RR for SCSC failure: 1.39 (CI: 1.04-1.81, p=0.035). However, the success rate in this group was still 62.5%, thus clearly indicating a clinically meaningful benefit. Conclusions: In our study, SCSC was feasible, safe and effective in order to prevent CIA in pts with PBC. All therapeutic subgroups benefited from SCSC. Although patients on E or ET are at higher risk for CIA, the success rate in this subgroup indicates that SCSC can be reasonably offered to patients subjected to NACT or ACT with epirubicin-containing regimens.

Citation Format: Kurbacher CM, Kurbacher AT, Herz S, Kolberg G, Kettelhoit N, Schweitzer C, Kurbacher JA, Eichler C. Safety and effectiveness of sensor-controlled scalp cooling to prevent alopecia in primary breast cancer patients receiving neoadjuvant or adjuvant epirubicin, taxanes, or both [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-11-14.

Abstract P4-10-17: Changes of bone turnover markers during perioperative anthracycline- and/or taxane-based chemotherapy in pre- and postmenopausal patients with primary breast cancer

Background: Loss of bone mineral density (BMD) is among the well known sequelae of pharmacological therapy of patients (pts) with primary breast cancer (PBC). Cancer therapy induced bone loss (CTIBL) progresses more rapidly as compared to normal age-related changes of BMD and is best known to be associated with aromatase inhibitors in postmenopausal pts. Chemotherapy (Ctx) may also lead to a deterioration of BMD but in contast to endocrine Tx, this phenomenon is by far less elucidated and, at least in younger pts, mostly interpreted as a secondary effect following Ctx induced ovarian failure. Previous investigations focused on the classical CMF scheme, whereas conclusive data regarding direct effects of more recent Ctx protocols on the bone metabolism of PBC pts are still lacking. This translational project was initiated to gain detailed insights into the influence of anthracycline (A)- and/or taxane (T)-based Ctx on bone turnover of both pre- and postmenopausal PBC pts in the clinical routine. Methods: Data of 109 pts (premenopausal: 49; postmenopausal: 60) with non-metastatic Ctx-naïve PBC exposed to neoadjuvant or adjuvant Ctx were analyzed. 84 pts (75%) had estrogen receptor-positive (ER+) disease, HER2- overexpression was found in 18 pts (17%). 16 pts (15%) received A-based Ctx, 34 pts (31%) received T-based Ctx, and 59 pts (54%) received A/T-based Ctx. Trastuzumab was given to 17 pts (16%) with HER2-positive disease. Serum bone markers including the C-telopeptide of type I collagen (ICTP) indicating osteoclast activity, the N-propeptide of type I collagen (P1NP) measuring osteoblast activity, and alkaline phosphatase (AP) were determined at baseline and prior to each subsequent Ctx cycle (C) up to C6. Changes of ICTP, P1NP, and AP over time were analyzed by repeated-measure ANOVA. Results: 600 Ctx cycles were analyzed. Baseline levels of ICTP (p = 0.0027), P1NP (p = 0.0063), and AP (p = 0.0007) were significantly higher in post- versus premenopausal pts. AP levels remained largely unchanged during Ctx. Trends showing an increase of ICTP from baseline until C6 in premenopausal pts and a decrease in postmenopausal pts did not reach statistical significance. In contrast, P1NP significantly declined in postmenopausal pts from baseline to C6 (p = 0.0152). In premenopausal pts, P1NP declined from baseline to C3 and thereafter increased to C6. These changes were highly significant (p = 0.0024). Conclusions: Our study represents one of the first systematic evaluations of bone turnover in pts exposed to modern A- and/or T-based Ctx for PBC in the clinical routine. Postmenopausal pts presented with higher baseline levels of all three markers which may be attributable to an enhanced bone turnover related to the loss of ovarian function prior to the initiation of Ctx. In postmenopausal pts, Ctx was associated with a sustained suppression of osteoblast activity whereas osteoblast suppression recovered until the end of Ctx in premenopausal pts. Whether these effects will translate into an increased risk of CTIBL remains a matter of further investigations which should clearly focus on the individual menopausal status.

Citation Format: Kurbacher CM, Rauschenbach N, Kurbacher AT, Sperling S, Herz S, Monreal K, Kurbacher JA. Changes of bone turnover markers during perioperative anthracycline- and/or taxane-based chemotherapy in pre- and postmenopausal patients with primary breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-10-17.

Abstract P4-13-22: Successful targeting HER2 in heavily pretreated HER2-negative metastatic breast cancer patients presenting with elevated serum levels of the HER2 extracellular domain and/or HER2 overexpressing circulating tumor cells

Background: A considerable proportion of patients (pts) with HER2-negative (HER2-) metastatic breast cancer (MBC) present with elevated serum levels of the soluble HER2 extracellular domain (sHER2) and/or HER2-overexpressing circulating tumor cells (CTCs) during their further clinical course. These "occult" HER2-positive (HER2+) pts may well be candidates for HER2-targeted therapy (Tx) albeit normally not subjected to such treatment. This observational study was undertaken to gain more insights into the feasibility of HER2-directed Tx in occult HER2+ MBC pts in the clinical routine. Methods: A total of 30 pts with heavily pretreated HER2- MBC (ER+, n = 26) showing sHER2 values > 15 ng/mL (n = 8), HER2+ CTCs (n = 7), or both (n = 15) were included. Pts had failed 2-16 prior systemic treatments (median: 7) and did not qualify for recruitment onto a controlled clinical trial. sHER was measured by a chemiluminescence assay (Siemens Helathcare, Eschborn, Germany), CTCs were ennumerated and checked for HER2 expression by using the FDA-cleared CellSearch™ technology (Veridex, Raritan, NJ). All pts received anti-HER2 Tx with trastuzumab (H: n = 18), lapatinib (L: n = 4), H+L (n = 2), or H+pertuzumab (H+P: n = 6). HER2-targeted Tx was given alone (n = 4), or in combination with endocrine agents (n = 7), cytotoxics (n = 17), or other targeted drugs (n = 2). Responses were scored according to RECIST 1.1, OS was calculated from the start of HER2-directed Ctx until death from any reason or loss to follow-up by using Kaplan-Meier statistics. Results: Anti-HER2 Tx was generally well tolerated. Median treatment duration was 16.1 wks (range 1.0-72.9 wks). In 2 pts with L and 1 pt with H+L, Tx was prematurely stopped due to toxicity (diarrhea, fatigue). 2 pts were too early to evaluate (TE). 11 PR, 12 SD, and 5 PD accounted for an objective response rate (ORR) of 36.7% and a clinical benefit rate (CBR) of 76.7%. Median OS was 62.9 wks. In 25 pts, 9 with PR, 12 with SD, and 4 with PD, results of serial sHER2 measurements at baseline and after 3 wks of Tx were available. Most pts with PD showed increasing sHER2 levels. In the majority of pts with PR or SD, sHER2 decreased by more than 20% from baseline. However, 2 pts with PR following L-based Tx showed increasing sHER2 values. In 19 pts, 8 with PR, 7 with SD, and 4 with PD, repeated CTC counts at week 6 from baseline were available. All pts with PD showed increasing CTCs. All pts with SD and PR presented with decreasing CTC counts, most of them normalizing within 6 wks. Conclusions: Our findings indicate that anti-HER2 Tx may be a valid option in pts with heavily pretreated HER2- MBC with pathological sHER2 values and/or HER2+ CTCs in the clinical routine. Thus, determination of both sHER2 and HER2 expression on CTCs appears to be reasonable in tissue HER2-negative MBC pts. Compared to sHER2, serial CTC measurements may be the more accurate predictor of response to anti-HER2 treatment, particularly in pts receiving L as part of their Tx. Results of ongoing randomized trials in this setting are eagerly awaited.

Citation Format: Kurbacher CM, Quade A, Eichler C, Kunstmann G, Herz S, Kurbacher JA, Warm MR. Successful targeting HER2 in heavily pretreated HER2-negative metastatic breast cancer patients presenting with elevated serum levels of the HER2 extracellular domain and/or HER2 overexpressing circulating tumor cells. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-22.

[Perioperative anesthesia management of extended partial liver resection. Pathophysiology of hepatic diseases and functional signs of hepatic failure]

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.

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.

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.

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.

Enzyme-Assisted Preparation of Isotope-Labeled 1-Deoxy-d-xylulose 5-Phosphate

Recombinant 1-deoxy-D-xylulose 5-phosphate synthase of Bacillus subtilis was used for the preparation of isotope-labeled 1-deoxy-D-xylulose 5-phosphate using isotope-labeled glucose and/or isotope-labeled pyruvate as starting materials. The simple one-pot methods described afford almost every conceivable isotopomer of 1-deoxy-D-xylulose 5-phosphate carrying (13)C or (14)C from commercially available precursors with an overall yield around 50%.

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 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.

Biosynthesis of terpenoids: YgbB protein converts 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate to 2C-methyl-D-erythritol 2,4-cyclodiphosphate

In many microorganisms, the putative orthologs of the Escherichia coli ygbB gene are tightly linked or fused to putative orthologs of ygbP, which has been shown earlier to be involved in terpenoid biosynthesis. The ygbB gene of E. coli was expressed in a recombinant E. coli strain and was shown to direct the synthesis of a soluble, 17-kDa polypeptide. The recombinant protein was found to convert 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate into 2C-methyl-D-erythritol 2,4-cyclodiphosphate and CMP. The structure of the reaction product was established by NMR spectroscopy using (13)C-labeled substrate samples. The enzyme-catalyzed reaction requires Mn(2+) or Mg(2+) but no other cofactors. Radioactivity from [2-(14)C]2C-methyl-D-erythritol 2,4-cyclodiphosphate was diverted efficiently to carotenoids by isolated chromoplasts from Capsicum annuum and, thus, was established as an intermediate in the deoxyxylulose phosphate pathway of isoprenoid biosynthesis. YgbB protein also was found to convert 4-diphosphocytidyl-2C-methyl-D-erythritol into 2C-methyl-D-erythritol 3,4-cyclophosphate. This compound does not serve as substrate for the formation of carotenoids by isolated chromoplasts and is assumed to be an in vitro product without metabolic relevance.

Biosynthesis of terpenoids: YchB protein of Escherichia coli phosphorylates the 2-hydroxy group of 4-diphosphocytidyl-2C-methyl-D-erythritol

A comparative analysis of all published complete genomes indicated that the putative orthologs of the unannotated ychB gene of Escherichia coli follow the distribution of the dxs, dxr, and ygbP genes, which have been shown to specify enzymes of the deoxyxylulose phosphate pathway of terpenoid biosynthesis, thus suggesting that the hypothetical YchB protein also is involved in that pathway. To test this hypothesis, the E. coli ychB gene was expressed in a homologous host. The recombinant protein was purified to homogeneity and was shown to phosphorylate 4-diphosphocytidyl-2C-methyl-D-erythritol in an ATP-dependent reaction. The reaction product was identified as 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate by NMR experiments with various (13)C-labeled substrate samples. A (14)C-labeled specimen of this compound was converted efficiently into carotenoids by isolated chromoplasts of Capsicum annuum. The sequence of E. coli YchB protein is similar to that of the protein predicted by the tomato cDNA pTOM41 (30% identity), which had been implicated in the conversion of chloroplasts to chromoplasts.

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.

Cytidine 5'-triphosphate-dependent biosynthesis of isoprenoids: YgbP protein of Escherichia coli catalyzes the formation of 4-diphosphocytidyl-2-C-methylerythritol

2-C-methylerythritol 4-phosphate has been established recently as an intermediate of the deoxyxylulose phosphate pathway used for biosynthesis of terpenoids in plants and in many microorganisms. We show that an enzyme isolated from cell extract of Escherichia coli converts 2-C-methylerythritol 4-phosphate into 4-diphosphocytidyl-2-C-methylerythritol by reaction with CTP. The enzyme is specified by the hitherto unannotated ORF ygbP of E. coli. The cognate protein was obtained in pure form from a recombinant hyperexpression strain of E. coli harboring a plasmid with the ygbP gene under the control of a T5 promoter and lac operator. By using the recombinant enzyme, 4-diphosphocytidyl-[2-(14)C]2-C-methylerythritol was prepared from [2-(14)C]2-C-methylerythritol 4-phosphate. The radiolabeled 4-diphosphocytidyl-2-C-methylerythritol was shown to be efficiently incorporated into carotenoids by isolated chromoplasts of Capsicum annuum. The E. coli ygbP gene appears to be part of a small operon also comprising the unannotated ygbB gene. Genes with similarity to ygbP and ygbB are present in the genomes of many microorganisms, and their occurrence appears to be correlated with that of the deoxyxylulose pathway of terpenoid biosynthesis. Moreover, several microorganisms have genes specifying putative fusion proteins with ygbP and ygbB domains, suggesting that both the YgbP protein and the YgbB protein are involved in the deoxyxylulose pathway. A gene from Arabidopsis thaliana with similarity to ygbP carries a putative plastid import sequence, which is well in line with the assumed localization of the deoxyxylulose pathway in the plastid compartment of plants.