Laboratory Evolution and Reverse Engineering of Clostridium thermocellum for Growth on Glucose and Fructose.

The native ability of Clostridium thermocellum to efficiently solubilize cellulose makes it an interesting platform for sustainable biofuel production through consolidated bioprocessing. Together with other improvements, industrial implementation of C. thermocellum, as well as fundamental studies into its metabolism, would benefit from improved and reproducible consumption of hexose sugars. To investigate growth of C. thermocellum on glucose or fructose, as well as the underlying molecular mechanisms, laboratory evolution was performed in carbon-limited chemostats with increasing concentrations of glucose or fructose and decreasing cellobiose concentrations. Growth on both glucose and fructose was achieved with biomass yields of 0.09 ± 0.00 and 0.18 ± 0.00 gbiomass gsubstrate-1, respectively, compared to 0.15 ± 0.01 gbiomass gsubstrate-1 for wild type on cellobiose. Single-colony isolates had no or short lag times on the monosaccharides, while wild type showed 42 ± 4 h on glucose and >80 h on fructose. With good growth on glucose, fructose, and cellobiose, the fructose isolates were chosen for genome sequence-based reverse metabolic engineering. Deletion of a putative transcriptional regulator (Clo1313_1831), which upregulated fructokinase activity, reduced lag time on fructose to 12 h with a growth rate of 0.11 ± 0.01 h-1 and resulted in immediate growth on glucose at 0.24 ± 0.01 h-1 Additional introduction of a G-to-V mutation at position 148 in cbpA resulted in immediate growth on fructose at 0.32 ± 0.03 h-1 These insights can guide engineering of strains for fundamental studies into transport and the upper glycolysis, as well as maximizing product yields in industrial settings.IMPORTANCEC. thermocellum is an important candidate for sustainable and cost-effective production of bioethanol through consolidated bioprocessing. In addition to unsurpassed cellulose deconstruction, industrial application and fundamental studies would benefit from improvement of glucose and fructose consumption. This study demonstrated that C. thermocellum can be evolved for reproducible constitutive growth on glucose or fructose. Subsequent genome sequencing, gene editing, and physiological characterization identified two underlying mutations with a role in (regulation of) transport or metabolism of the hexose sugars. In light of these findings, such mutations have likely (and unknowingly) also occurred in previous studies with C. thermocellum using hexose-based media with possible broad regulatory consequences. By targeted modification of these genes, industrial and research strains of C. thermocellum can be engineered to (i) reduce glucose accumulation, (ii) study cellodextrin transport systems in vivo, (iii) allow experiments at >120 g liter-1 soluble substrate concentration, or (iv) reduce costs for labeling studies.

Metabolic Fluxes of Nitrogen and Pyrophosphate in Chemostat Cultures of Clostridium thermocellum and Thermoanaerobacterium saccharolyticum.

Clostridium thermocellum and Thermoanaerobacterium saccharolyticum were grown in cellobiose-limited chemostat cultures at a fixed dilution rate. C. thermocellum produced acetate, ethanol, formate, and lactate. Surprisingly, and in contrast to batch cultures, in cellobiose-limited chemostat cultures of T. saccharolyticum, ethanol was the main fermentation product. Enzyme assays confirmed that in C. thermocellum, glycolysis proceeds via pyrophosphate (PPi)-dependent phosphofructokinase (PFK), pyruvate-phosphate dikinase (PPDK), as well as a malate shunt for the conversion of phosphoenolpyruvate (PEP) to pyruvate. Pyruvate kinase activity was not detectable. In T. saccharolyticum, ATP but not PPi served as cofactor for the PFK reaction. High activities of both pyruvate kinase and PPDK were present, whereas the activities of a malate shunt enzymes were low in T. saccharolyticum In C. thermocellum, glycolysis via PPi-PFK and PPDK obeys the equation glucose + 5 NDP + 3 PPi → 2 pyruvate + 5 NTP + Pi (where NDP is nucleoside diphosphate and NTP is nucleoside triphosphate). Metabolic flux analysis of chemostat data with the wild type and a deletion mutant of the proton-pumping pyrophosphatase showed that a PPi-generating mechanism must be present that operates according to ATP + Pi → ADP + PPi Both organisms also produced significant amounts of amino acids in cellobiose-limited cultures. It was anticipated that this phenomenon would be suppressed by growth under nitrogen limitation. Surprisingly, nitrogen-limited chemostat cultivation of wild-type C. thermocellum revealed a bottleneck in pyruvate oxidation, as large amounts of pyruvate and amino acids, mainly valine, were excreted; up to 50% of the nitrogen consumed was excreted again as amino acids.IMPORTANCE This study discusses the fate of pyrophosphate in the metabolism of two thermophilic anaerobes that lack a soluble irreversible pyrophosphatase as present in Escherichia coli but instead use a reversible membrane-bound proton-pumping enzyme. In such organisms, the charging of tRNA with amino acids may become more reversible. This may contribute to the observed excretion of amino acids during sugar fermentation by Clostridium thermocellum and Thermoanaerobacterium saccharolyticum Calculation of the energetic advantage of reversible pyrophosphate-dependent glycolysis, as occurs in Clostridium thermocellum, could not be properly evaluated, as currently available genome-scale models neglect the anabolic generation of pyrophosphate in, for example, polymerization of amino acids to protein. This anabolic pyrophosphate replaces ATP and thus saves energy. Its amount is, however, too small to cover the pyrophosphate requirement of sugar catabolism in glycolysis. Consequently, pyrophosphate for catabolism is generated according to ATP + Pi → ADP + PPi.

[Diagnosis and management of vascular malformations : Interdisciplinary teamwork in demand]. / Diagnostik und Management von Gefäßmalformationen : Interdisziplinäres Teamwork gefragt.

Vascular anomalies are very rare, but can occur in children and adults in almost every region of the body. Due to the complexity of this disease, the path to a definitive diagnosis is often difficult. It requires interdisciplinary teamwork with close exchange of information between the individual treatment partners to reach the correct diagnosis and then to start the best therapy. This article provides an overview of the main types of vascular malformations from a clinical, imaging, and histological point of view, following the current classification of the International Society for the Study of Vascular Anomalies (ISSVA).

[Successful pembrolizumab therapy in metastasized adenosquamous carcinoma of the colon]. / Erfolgreiche Pembrolizumab-Therapie bei metastasiertem adenosquamösem Karzinom des Kolons.

Adenosquamous carcinoma (ASqC) is an exceedingly rare subtype of colorectal cancer without any known special guidelines for treatment. The biological behaviour and molecular background are widely unknown, although a few case studies report a worse prognosis compared to ordinary colorectal adenocarcinoma. We herein report for the first time the successful immune checkpoint inhibitor therapy in a 40-year-old patient suffering from metastasized right-sided colonic ASqC with unique molecular features, after having previously progressed under standard chemotherapy.

Correction to: Antithrombotic therapy after mitral valve repair: VKA or aspirin?

The original version of this article unfortunately contained a mistake in the author name. The co-author name should be Frederikus A. Klok instead of Frederik A. Klok. The original article has been corrected.

Antithrombotic therapy after mitral valve repair: VKA or aspirin?

The optimal antithrombotic therapy following mitral valve repair (MVr) is still a matter of debate. Therefore, we evaluated the rate of thromboembolic and bleeding complications of two antithrombotic prevention strategies: vitamin K antagonists (VKA) versus aspirin. Consecutive patients who underwent MVr between 2004 and 2016 at three Dutch hospitals were evaluated for thromboembolic and bleeding complications during three postoperative months. The primary endpoint was the combined incidence of thromboembolic and bleeding complications to determine the net clinical benefit of VKA strategy as compared with aspirin. Secondary objectives were to evaluate both thromboembolic and bleeding rates separately and to identify predictors for both complications. A total of 469 patients were analyzed, of whom 325 patients (69%) in the VKA group and 144 patients (31%) in the aspirin group. Three months postoperatively, the cumulative incidence of the combined end point of the study was 9.2% (95%CI 6.1-12) in the VKA group and 11% (95%CI 6.0-17) in the aspirin group [adjusted hazard ratio (HR) 1.6, 95%CI 0.83-3.1]. Moreover, no significant differences were observed in thromboembolic rates (adjusted HR 0.82, 95%CI 0.16-4.2) as well as in major bleeding rates (adjusted HR 1.89, 95%CI 0.90-3.9). VKA and aspirin therapy showed a similar event rate of 10% during 3 months after MVr in patients without prior history of AF. In both treatment groups thromboembolic event rate was low and major bleeding rates were comparable. Future prospective, randomized trials are warranted to corroborate our findings.

The ethanol pathway from Thermoanaerobacterium saccharolyticum improves ethanol production in Clostridium thermocellum.

Clostridium thermocellum ferments cellulose, is a promising candidate for ethanol production from cellulosic biomass, and has been the focus of studies aimed at improving ethanol yield. Thermoanaerobacterium saccharolyticum ferments hemicellulose, but not cellulose, and has been engineered to produce ethanol at high yield and titer. Recent research has led to the identification of four genes in T. saccharolyticum involved in ethanol production: adhE, nfnA, nfnB and adhA. We introduced these genes into C. thermocellum and observed significant improvements to ethanol yield, titer, and productivity. The four genes alone, however, were insufficient to achieve in C. thermocellum the ethanol yields and titers observed in engineered T. saccharolyticum strains, even when combined with gene deletions targeting hydrogen production. This suggests that other parts of T. saccharolyticum metabolism may also be necessary to reproduce the high ethanol yield and titer phenotype in C. thermocellum.

Deletion of Type I glutamine synthetase deregulates nitrogen metabolism and increases ethanol production in Clostridium thermocellum.

Clostridium thermocellum rapidly deconstructs cellulose and ferments resulting hydrolysis products into ethanol and other products, and is thus a promising platform organism for the development of cellulosic biofuel production via consolidated bioprocessing. While recent metabolic engineering strategies have targeted eliminating canonical fermentation products (acetate, lactate, formate, and H2), C. thermocellum also secretes amino acids, which has limited ethanol yields in engineered strains to approximately 70% of the theoretical maximum. To investigate approaches to decrease amino acid secretion, we attempted to reduce ammonium assimilation by deleting the Type I glutamine synthetase (glnA) in an essentially wild type strain of C. thermocellum. Deletion of glnA reduced levels of secreted valine and total amino acids by 53% and 44% respectively, and increased ethanol yields by 53%. RNA-seq analysis revealed that genes encoding the RNF-complex were more highly expressed in ΔglnA and may have a role in improving NADH-availability for ethanol production. While a significant up-regulation of genes involved in nitrogen assimilation and urea uptake suggested that deletion of glnA induces a nitrogen starvation response, metabolomic analysis showed an increase in intracellular glutamine levels indicative of nitrogen-rich conditions. We propose that deletion of glnA causes deregulation of nitrogen metabolism, leading to overexpression of nitrogen metabolism genes and, in turn, elevated glutamine levels. Here we demonstrate that perturbation of nitrogen assimilation is a promising strategy to redirect flux from the production of nitrogenous compounds toward biofuels in C. thermocellum.

[Hyperthyroid and acute tonsillitis in a 23-year-old woman]. / Hyperthyreose und akute Tonsillitis bei einer 23-jährigen Patientin.

A 23-year-old woman with preexisting Graves' disease who received thiamazole treatment presented with fever, dysphagia, hyperthyroidism and leukopenia. With suspicion of thyreotoxicosis accompanied by drug-induced agranulocytosis she was successfully managed by plasmapheresis, G­CSF administration and inhibition of periphereal conversion of thyroid hormones. In due course she underwent thyroidectomy. Thiamazole is frequently associated with drug-induced agranulocytosis. Long-term therapy with thiamazole requires critical evaluation and alternatives should be considered early. Plasmapheresis is an adequate treatment option to achieve normal thyroid hormonal status.

Ten-year patterns in blood product utilization during cardiothoracic surgery with cardiopulmonary bypass in a tertiary hospital.

BACKGROUND: This retrospective analysis describes blood conservation strategies and overall consumption of red blood cells (RBCs), fresh-frozen plasma (FFP), and platelet (PLT) concentrates during nonaortic cardiac surgery with cardiopulmonary bypass (CPB) in a tertiary hospital over a 10-year period. STUDY DESIGN AND METHODS: Study variables of 6026 patients that underwent cardiac surgery between 2002 and 2011 were incorporated in the database and included hemoglobin (Hb), lowest temperature, CPB duration, 24-hour blood loss, fluid balance, and overall transfusion requirements. RESULTS: Between 2002 and 2011, the lowest intraoperative Hb levels and temperature increased from 8.5 ± 1.2 to 10.4 ± 1.4 g/dL and from 32 ± 2 to 34 ± 1°C, respectively. In addition to the steep decrease in the postoperative fluid balance over time, a reduction in 24-hour blood loss from 815 ± 588 mL (2002) to 590 ± 438 mL (2011) was observed. These changes were paralleled by a 28% reduction in overall RBC transfusion from 1443 units in 2002 to 1038 in 2011. While RBC transfusion decreased over time, there was no significant change in the use of FFP or PLT concentrate transfusion. The probability to receive RBC transfusion increased after cessation of aprotinin, but reduced after routine cell salvage in all operations. CONCLUSION: This institutional report shows a large reduction in blood loss and transfusion requirements in cardiac surgery over a 10-year period. This reduction is most probably attributed to structural cell salvage, reduced intraoperative fluid volumes, and the increase in the lowest intraoperative body temperature.

Microcirculatory perfusion is preserved during off-pump but not on-pump cardiac surgery.

OBJECTIVE: This study investigated the perioperative course of microcirculatory perfusion in off-pump compared with on-pump surgery. Additionally, the impact of changes in systemic hemodynamics, hematocrit, and body temperature was studied. DESIGN: Prospective, nonrandomized, observational study. SETTING: Tertiary university hospital. PARTICIPANTS: Patients undergoing coronary artery bypass grafting with (n = 13) or without (n = 13) use of cardiopulmonary bypass. INTERVENTIONS: Microcirculatory measurements were obtained at 5 time points ranging from induction of anesthesia to ICU admission. MEASUREMENTS AND MAIN RESULTS: Microcirculatory recordings were performed with sublingual sidestream dark field imaging. Despite a comparable reduction in intraoperative blood pressure between groups, the perfused vessel density decreased more than 20% after onset of extracorporeal circulation but remained stable in the off-pump group. The reduction in microvascular perfusion in the on-pump group was further paralleled by decreased hematocrit and temperature. Although postbypass hematocrit levels and body temperature were restored to similar levels as in the off-pump group, the median microvascular flow index remained reduced after bypass (2.4 [2.3-2.7]) compared with baseline (2.8 [2.7-2.9]; p = 0.021). CONCLUSIONS: Microcirculatory perfusion remained unaltered throughout off-pump surgery. In contrast, microvascular perfusion declined after initiation of cardiopulmonary bypass and did not recover in the early postoperative phase.

Characterization of sugarcane bagasse solubilization and utilization by thermophilic cellulolytic and saccharolytic bacteria at increasing solid loadings.

In Brazil the main feedstock used for ethanol production is sugarcane juice, resulting in large amounts of bagasse. Bagasse has high potential for cellulosic ethanol production, and consolidated bioprocessing (CBP) has potential for lowering costs. However, economic feasibility requires bioprocessing at high solids loadings, entailing engineering and biological challenges. This study aims to document and characterize carbohydrate solubilization and utilization by defined cocultures of Clostridium thermocellum and Thermoanaerobacterium thermosaccharolyticum at increasing loadings of sugarcane bagasse. Results show that fractional carbohydrate solubilization decreases as solids loading increases from 10 g/L to 80 g/L. Cocultures enhance solubilization and carbohydrate utilization compared to monocultures, irrespective of initial solids loading. Rinsing bagasse before fermentation slightly decreases solubilization. Experiments studying inhibitory effects using spent media and dilution of broth show that negative effects are temporary or reversible. These findings highlight the potential of converting sugarcane bagasse via CBP, pointing out performance limitations that must be addressed.

Enhancing anaerobic digestion of lignocellulosic biomass by mechanical cotreatment.

BACKGROUND: The aim of this study was to increase the accessibility and accelerate the breakdown of lignocellulosic biomass to methane in an anaerobic fermentation system by mechanical cotreatment: milling during fermentation, as an alternative to conventional pretreatment prior to biological deconstruction. Effluent from a mesophilic anaerobic digester running with unpretreated senescent switchgrass as the predominant carbon source was collected and subjected to ball milling for 0.5, 2, 5 and 10 min. Following this, a batch fermentation test was conducted with this material in triplicate for an additional 18 days with unmilled effluent as the 'status quo' control. RESULTS: The results indicate 0.5 - 10 min of cotreatment increased sugar solubilization by 5- 13% when compared to the unmilled control, with greater solubilization correlated with increased milling duration. Biogas concentrations ranged from 44% to 55.5% methane with the balance carbon dioxide. The total biogas production was statistically higher than the unmilled control for all treatments with 2 or more minutes of milling (α = 0.1). Cotreatment also decreased mean particle size. Energy consumption measurements of a lab-scale mill indicate that longer durations of milling offer diminishing benefits with respect to additional methane production. CONCLUSIONS: Cotreatment in anaerobic digestion systems, as demonstrated in this study, provides an alternative approach to conventional pretreatments to increase biogas production from lignocellulosic grassy material.

Solubilization of sugarcane bagasse by mono and cocultures of thermophilic anaerobes with and without cotreatment.

Cotreatment, mechanical disruption of lignocellulosic biomass during microbial fermentation, is a potential alternative to thermochemical pretreatment as a means of increasing the accessibility of lignocellulose to biological attack. Successful implementation of cotreatment requires microbes that can withstand milling, while solubilizing and utilizing carbohydrates from lignocellulose. In this context, cotreatment with thermophilic, lignocellulose-fermenting bacteria has been successfully evaluated for a number of lignocellulosic feedstocks. Here, cotreatment was applied to sugarcane bagasse using monocultures of the cellulose-fermenting Clostridium thermocellum and cocultures with the hemicellulose-fermenting Thermoanaerobacterium thermosaccharolyticum. This resulted in 76 % carbohydrate solubilization (a 1.8-fold increase over non-cotreated controls) on 10 g/L solids loading, having greater effect on the hemicellulose fraction. With cotreatment, fermentation by wild-type cultures at low substrate concentrations increased cumulative product formation by 45 % for the monoculture and 32 % for the coculture. These findings highlight the potential of cotreatment for enhancing deconstruction of sugarcane bagasse using thermophilic bacteria.

Unmasking of a Giant Coronary Aneurysm by Chronic Total Coronary Occlusion Percutaneous Coronary Intervention Techniques.

A young female patient presenting with a non-ST-segment elevation myocardial infarction underwent invasive coronary angiography, revealing a total occlusion of the right coronary artery. During percutaneous coronary intervention with dual catheter access, a retrograde tip injection and peculiar retrograde wiring unmasked a giant coronary aneurysm, which noninvasive imaging confirmed.

Intraoperative cell salvage is associated with reduced postoperative blood loss and transfusion requirements in cardiac surgery: a cohort study.

BACKGROUND: This study investigated whether implementation of cell salvage of shed mediastinal and residual blood in all patients undergoing low-to-moderate-risk cardiac surgery reduces the need for allogeneic red blood cell (RBC) transfusion compared to patients not subjected to cell salvage. STUDY DESIGN AND METHODS: This retrospective cohort study included patients undergoing low-to-moderate-risk cardiac surgery with cardiopulmonary bypass without (control; n = 531) or with cell salvage (n = 433; Autolog, Medtronic). Study endpoints, including 24-hour blood loss and RBC requirements, were evaluated using adjusted logistic regression. RESULTS: Baseline characteristics were similar between groups. The cell saver group received 568 ± 267 mL of autologous blood. Median number of allogeneic RBC transfusions was higher in the control group (2 [1-5]) compared with the cell salvage group (1 [0-3]; p < 0.001). There were no clinically relevant differences in postoperative coagulation test results between groups. The relative risk (RR) for postoperative RBC transfusion was reduced to 0.76 (95% confidence interval [CI], 0.70-0.83; p < 0.0001) in the cell salvage group. Moreover, patients in the cell salvage group had a lower chance for myocardial infarction (RR, 0.26; 95% CI, 0.08-0.91; p = 0.035), whereas the cell salvage group was associated with a higher probability for intensive care discharge within 24 hours after surgery (RR, 1.08; 95% CI, 1.02-1.14; p = 0.009). CONCLUSION: The use of cell salvage throughout the entire procedure reduces postoperative blood loss and allogeneic RBC transfusion. These findings advocate implementation of cell salvage in all patients undergoing on-pump cardiac surgery, irrespective of anticipated surgery-related blood loss.

Testing alternative kinetic models for utilization of crystalline cellulose (Avicel) by batch cultures of Clostridium thermocellum.

Descriptive kinetics of batch cellulose (Avicel) and cellobiose fermentation by Clostridium thermocellum were examined with residual substrate and biosynthate concentrations inferred based on elemental analysis. Biosynthate was formed in constant proportion to substrate consumption until substrate was exhausted for cellobiose fermentation, and until near the point of substrate exhaustion for cellulose fermentation. Cell yields (g pellet biosynthate carbon/g substrate carbon) of 0.214 and 0.200 were obtained for cellulose and cellobiose, respectively. For cellulose fermentation a sigmoidal curve fit was applied to substrate and biosynthate concentrations over time, which was then differentiated to calculate instantaneous rates of growth and substrate consumption. Three models were tested to describe the kinetics of Avicel utilization by C. thermocellum: (A) first order in cells, (B) first order in substrate, and (C) first order in cells and substrate, and second order overall. Models (A) and (B) have been proposed in the literature to describe cultures of cellulolytic microorganisms, whereas model (C) has not. Of the three models tested, model (c) provided by far the best fit to batch culture data. A second order rate constant equal to 0.735 L g C(-1) h(-1) was found for utilization of Avicel by C. thermocellum. Adding an endogenous metabolism term improved the descriptive quality of the model as substrate exhaustion was approached. Such rate constants may in the future find utility for describing and comparing cellulose fermentation involving other microbes and other substrates.

Development and evaluation of methods to infer biosynthesis and substrate consumption in cultures of cellulolytic microorganisms.

Concentrations of biosynthate (microbial biomass plus extracellular proteins) and residual substrate were inferred using elemental analysis for batch cultures of Clostridium thermocellum. Inferring residual substrate based on elemental analysis for a cellulose (Avicel)-grown culture shows similar results to residual substrate determined by quantitative saccharification using acid hydrolysis. Inference based on elemental analysis is also compared to different on-line measurements: base addition, CO2 production, and Near Infra Red optical density (OD850 ). Of these three on-line techniques, NIR OD850 has the best correlation with residual substrate concentration and is the most practical to use. Both biosynthate and residual substrate concentration demonstrate typical sigmoidal trends that can easily be fitted with a five-parameter Richards curve. The sigmoidal character of the inferred concentrations and on-line data, especially the CO2 production rate, suggest that there is a maximum in cell-specific rates of growth and substrate utilization during batch fermentations of crystalline cellulose, which is not observed during grown on cellobiose. Using a sigmoidal fit curve, the instantaneous specific growth rate was determined. While soluble substrate grown cultures show a constant growth rate, cultures grown on solid substrate do not. Features of various approaches are compared, with some more appropriate for rapid general indication of metabolic activity and some more appropriate for quantitative physiological studies.

Macrophages promote tumour growth and liver metastasis in an orthotopic syngeneic mouse model of colon cancer.

PURPOSE: Tumour-associated macrophages have been shown to promote proliferation, angiogenesis and metastasis in several carcinomas. The effect on colon cancer has not yet been clarified. Furthermore, Kupffer cells in the liver might initiate the formation of metastases by directly binding tumour cells. METHODS: An orthotopic syngeneic mouse model of colon cancer as well as a liver metastases model has been studied, using murine CT-26 colon cancer cells in Balb/c-mice. Macrophages were depleted in both models by clodronate liposomes. Tumour sizes and metastases were determined using 7-Tesla MRI. The macrophage and vascular density in the orthotopic tumours as well as the Kupffer cell density in the livers were evaluated using immunohistochemistry. RESULTS: Animals in the macrophage-depleted group displayed significantly smaller primary tumours (37 ± 20 mm(3)) compared to the control group (683 ± 389 mm(3), p = 0.0072). None of the mice in the depleted group showed liver or peritoneal metastases, whereas four of six control mice displayed liver and five out of six mice peritoneal metastases. The vascular density was significantly lower in the macrophage-depleted group (p = 0.0043). In the liver metastases model, animals of the Kupffer cell-depleted group (14.3 ± 7.7) showed significantly less liver metastases than mice of the two control groups (PBS liposomes, 118.5 ± 28.2, p = 0.0117; NaCl, 81.7 ± 23.2, p = 0.0266). The number of liver metastases correlated directly with the Kupffer cell density (p = 0.0221). CONCLUSION: Macrophages promote tumour growth, angiogenesis and metastases in this orthotopic syngeneic mouse model. Kupffer cells enhance the formation of metastases in the liver.

MR microscopy of the human finger and correlation with histology--a proof-of-principle study.

Magnetic resonance imaging (MRI) with small surface coils is a well established method for the diagnostic evaluation of finger masses. Until now, histological examination has been required to reliably assess tumor extent and infiltration of surrounding structures. Ultra-high-field MR microscopy (MRM) allows evaluation of anatomical structures and pathologies with submillimeter resolution. This study describes the diagnostic prospects and potential of MRM based on the ex-vivo examination of different finger pathologies. Ten human digits were examined by ex-vivo MRM at 7.1 Tesla (ClinScan, Bruker BioScan) using a T2-weighted turbo spin echo (TSE) sequence. Imaging parameters were: TE 48 ms; TR 8370 ms; slice thickness 700 µm; matrix size 1024 × 1024 pixels; FOV 37 × 37 mm; in-plane resolution 36 × 36 µm/voxel. Afterwards specimens were examined histologically. Histology and MRM were correlated. MRM allowed evaluation of the anatomy of the nail, the tendon insertions, the distal interphalangeal joint, and the neurovascular bundles. Finger abnormalities evaluated by MRM included osteomyelitis and metastatic disease. Subsequent histological examination confirmed MRM findings regarding origin, internal makeup, and extent of the structures visualized. This study demonstrates the potential of MRM for imaging small anatomical structures and pathologies of the human finger. Our ex-vivo findings correlate strongly with histology, suggesting that MRM may gain a central role in assessing anatomical structures and pathology in terms of morphology, extent, and infiltration of surrounding structures. Therefore, with increasing availability, MRM is expected to become an essential tool not only in experimental studies but also for daily routine.