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Endangered species of hosts are coupled with endangered species of parasites, which share the risk of co-extinction. Conservation efforts sometimes include breeding of rare species in captivity. Data on parasites of captive populations of endangered species is scarce and the ability of small numbers of captive host individuals to support the biodiversity of native parasites is limited. Examination of ectosymbionts of the critically endangered Philippine eagles and the endangered Mindanao Hawk-Eagle kept at the Philippine Eagle Center, Philippines, revealed three feather mite species despite regular treatment with insecticide powder. No other ectosymbiont taxa were detected. Studies in morphology and molecular phylogeny of these feather mites based on mitochondrial and nuclear DNA markers indicate that species found were typical for Accipitridae. Three new pterolichoid feather mite species (Acari: Pterolichoidea) were described from two species of eagles (Accipitriformes: Accipitridae) endemic to the Philippines: Hieracolichus philippinensis sp. n. (Gabuciniidae) and Pseudalloptinus pithecophagae sp. n. (Pterolichidae) from the Great Philippine Eagle Pithecophaga jefferyi Ogilvie-Grant, 1896, and Pseudogabucinia nisaeti sp. n. (Kramerellidae) from the Mindanao Hawk-Eagle Nisaetus pinskeri Gould, 1863. The presence of H. philippinensis on P. jefferyi supports the recent finding that the Great Philippine Eagle belongs to the lineage of serpent eagles (Circaetinae) rather than to the Harpy and other eagles.
Background: Molecular hydrogen (H2) is an attractive future energy carrier to replace fossil fuels. Biologically and sustainably produced H2 could contribute significantly to the future energy mix. However, biological H2 production methods are faced with multiple barriers including substrate cost, low production rates, and low yields. The C1 compound formate is a promising substrate for biological H2 production, as it can be produced itself from various sources including electrochemical reduction of CO2 or from synthesis gas. Many microbes that can produce H2 from formate have been isolated; however, in most cases H2 production rates cannot compete with other H2 production methods.
Results: We established a formate-based H2 production method utilizing the acetogenic bacterium Acetobacterium woodii. This organism can use formate as sole energy and carbon source and possesses a novel enzyme complex, the hydrogen-dependent CO2 reductase that catalyzes oxidation of formate to H2 and CO2. Cell suspensions reached specific formate-dependent H2 production rates of 71 mmol g protein −1 h−1 (30.5 mmol g CDW −1 h−1) and maximum volumetric H2 evolution rates of 79 mmol L−1 h−1. Using growing cells in a two-step closed batch fermentation, specific H2 production rates reached 66 mmol g CDW −1 h−1 with a volumetric H2 evolution rate of 7.9 mmol L−1 h−1. Acetate was the major side product that decreased the H2 yield. We demonstrate that inhibition of the energy metabolism by addition of a sodium ionophore is suitable to completely abolish acetate formation. Under these conditions, yields up to 1 mol H2 per mol formate were achieved. The same ionophore can be used in cultures utilizing formate as specific switch from a growing phase to a H2 production phase.
Conclusions: Acetobacterium woodii reached one of the highest formate-dependent specific H2 productivity rates at ambient temperatures reported so far for an organism without genetic modification and converted the substrate exclusively to H2. This makes this organism a very promising candidate for sustainable H2 production and, because of the reversibility of the A. woodii enzyme, also a candidate for reversible H2 storage.
Stress-induced cell surface expression of MHC class I-related glycoproteins of the MIC and ULBP families allows for immune recognition of dangerous “self cells” by human cytotoxic lymphocytes via the NKG2D receptor. With two MIC molecules (MICA and MICB) and six ULBP molecules (ULBP1–6), there are a total of eight human NKG2D ligands (NKG2DL). Since the discovery of the NKG2D–NKG2DL system, the cause for both redundancy and diversity of NKG2DL has been a major and ongoing matter of debate. NKG2DL diversity has been attributed, among others, to the selective pressure by viral immunoevasins, to diverse regulation of expression, to differential tissue expression as well as to variations in receptor interactions. Here, we critically review the current state of knowledge on the poorly studied human NKG2DL ULBP4. Summarizing available facts and previous studies, we picture ULBP4 as a peculiar ULBP family member distinct from other ULBP family members by various aspects. In addition, we provide novel experimental evidence suggesting that cellular processing gives rise to mature ULBP4 glycoproteins different to previous reports. Finally, we report on the proteolytic release of soluble ULBP4 and discuss these results in the light of known mechanisms for generation of soluble NKG2DL.
This article advances the argument that quality of democracy depends not only on the performance of democratic institutions but also on the dispositions of citizens. We make three contributions to the study of democratic quality. First, we develop a fine-grained, structured conceptualization of the three core dispositions (democratic commitments, political capacities, and political participation) that make up the citizen component of democratic quality. Second, we provide a more precise account of the notion of inter-component congruence or "fit" between the institutional and citizen components of democratic quality, distinguishing between static and dynamic forms of congruence. Third, drawing on cross-national data, we show the importance of taking levels of inter-dispositional consistency into account when measuring democratic quality.
Despite multidisciplinary local and systemic therapeutic approaches, the prognosis for most patients with brain metastases is still dismal. The role of adaptive and innate anti-tumor response including the Human Leukocyte Antigen (HLA) machinery of antigen presentation is still unclear. We present data on the HLA class II-chaperone molecule CD74 in brain metastases and its impact on the HLA peptidome complexity.
We analyzed CD74 and HLA class II expression on tumor cells in a subset of 236 human brain metastases, primary tumors and peripheral metastases of different entities in association with clinical data including overall survival. Additionally, we assessed whole DNA methylome profiles including CD74 promoter methylation and differential methylation in 21 brain metastases. We analyzed the effects of a siRNA mediated CD74 knockdown on HLA-expression and HLA peptidome composition in a brain metastatic melanoma cell line.
We observed that CD74 expression on tumor cells is a strong positive prognostic marker in brain metastasis patients and positively associated with tumor-infiltrating T-lymphocytes (TILs). Whole DNA methylome analysis suggested that CD74 tumor cell expression might be regulated epigenetically via CD74 promoter methylation. CD74high and TILhigh tumors displayed a differential DNA methylation pattern with highest enrichment scores for antigen processing and presentation. Furthermore, CD74 knockdown in vitro lead to a reduction of HLA class II peptidome complexity, while HLA class I peptidome remained unaffected.
In summary, our results demonstrate that a functional HLA class II processing machinery in brain metastatic tumor cells, reflected by a high expression of CD74 and a complex tumor cell HLA peptidome, seems to be crucial for better patient prognosis.
Rationale: With advances in contemporary radiotherapy techniques, and as cancer survival improves, severe isolated coronary ostial disease may develop many years following mediastinal radiotherapy, even in the absence of classical cardiovascular risk factors.
Patient concerns: We describe the case of a 73-year-old woman with previous chest radiotherapy for breast cancer who underwent coronary artery bypass graft surgery for severe bilateral coronary ostial lesions.
Diagnoses: Coronary angiography demonstrated severe, isolated bilateral coronary ostial lesions.
Interventions: The patient underwent urgent coronary artery bypass graft surgery to treat her critical coronary artery disease.
Outcomes: Intra-operatively, internal mammary arteries were not amenable to harvesting due to very dense mediastinal adhesions. Therefore, saphenous vein grafts were performed to the left anterior descending, distal left circumflex, obtuse marginal and distal right coronary arteries. The patient made a satisfactory in-hospital recovery, and was subsequently discharged back to her local hospital for rehabilitation.
Lessons: Patients successfully treated with mediastinal radiotherapy require careful long-term follow-up for the assessment of radiation-induced coronary artery disease. Importantly, mediastinal irradiation may preclude internal mammary artery utilization, and thus alter the strategy for surgical myocardial revascularization.
During the Holocene, North American ice sheet collapse and rapid sea-level rise reconnected the Black Sea with the global ocean. Rapid meltwater releases into the North Atlantic and associated climate change arguably slowed the pace of Neolithisation across southeastern Europe, originally hypothesized as a catastrophic flooding that fueled culturally-widespread deluge myths. However, we currently lack an independent record linking the timing of meltwater events, sea-level rise and environmental change with the timing of Neolithisation in southeastern Europe. Here, we present a sea surface salinity record from the Northern Aegean Sea indicative of two meltwater events at ~8.4 and ~7.6 kiloyears that can be directly linked to rapid declines in the establishment of Neolithic sites in southeast Europe. The meltwater events point to an increased outflow of low salinity water from the Black Sea driven by rapid sea level rise >1.4 m following freshwater outbursts from Lake Agassiz and the final decay of the Laurentide ice sheet. Our results shed new light on the link between catastrophic sea-level rise and the Neolithisation of southeastern Europe, and present a historical example of how coastal populations could have been impacted by future rapid sea-level rise.
We investigate whether and how the shift from discretionary forward-looking provisioning to the restrictive incurred loss approach under International Financial Reporting Standards (IFRS) in the European Union (EU) affects the cross-country comparability and predictive ability of loan loss allowances. Given bank supervisors’ keen interest in comparable and adequate loan loss allowances, we also examine the role of supervisors in determining financial statement effects around IFRS adoption. We find that the application of the incurred loss approach has led to more comparable loan loss allowances. However, some differences persist in countries where supervisors were reluctant to enforce the incurred loss approach. Our results also suggest that the predictive ability of loan loss allowances improved following IFRS adoption. Finally, in supplemental analyses we document that increased comparability of loan loss allowances is associated with the cross-country convergence of the risk sensitivity of bank leverage indicating an improvement in the effectiveness of market discipline in the EU.
Background: The Indonesian region of Aceh was the area most severely affected by the earthquake and tsunami of 26 December 2004. Department of Health data reveal an upward trend of dengue cases in Aceh since the events of the tsunami. Despite the increasing incidence of dengue in the region, there is limited understanding of dengue among the general population of Aceh. The aim of this study was to assess the knowledge, attitude, and practice (KAP) regarding dengue among the people of Aceh, Indonesia in order to design intervention strategies for an effective dengue prevention program.
Methods: A community-based cross-sectional study was conducted in Aceh between November 2014 and March 2015 with a total of 609 participants living in seven regencies and two municipalities. Information on the socio-demographic characteristics of participants and their KAP regarding dengue was collected using a pre-tested structured questionnaire. The KAP status (good vs. poor) of participants with different socio-demographic characteristics was compared using Chi Square-test, ANOVA or Fisher’s exact test as appropriate. Logistic regression analysis was used to determine the predictors of each KAP domain.
Results: We found that 45% of participants had good knowledge regarding dengue and only 32% had good attitudes and good dengue preventive practices. There was a significant positive correlation between knowledge and attitudes, knowledge and practice, and attitudes and practice. In addition, people who had good knowledge were 2.7 times more likely to have good attitudes, and people who had good attitudes were 2.2 times more likely to have good practices regarding dengue. The level of education, occupation, marital status, monthly income, socioeconomic status (SES) and living in the city were associated with the knowledge level. Occupation, SES, and having experienced dengue fever were associated with attitudes. Education, occupation, SES and type of residence were associated with preventive practices.
Conclusion: Our study suggests that dengue prevention programs are required to increase KAP levels regarding dengue in the communities of Aceh.
Genetic heterogeneity of primary lesion and metastasis in small intestine neuroendocrine tumors
(2018)
Data on intratumoral heterogeneity of small intestine neuroendocrine tumors (SI-NETs) and related liver metastasis are limited. The aim of this study was to characterize genetic heterogeneity of 5 patients with SI-NETs. Therefore, formalin-fixed, paraffin-embedded tissue samples of primary and metastatic lesions as well as benign liver of five patients with synchronously metastasized, well differentiated SI-NETs were analyzed with whole exome sequencing. For one patient, chip based 850k whole DNA methylome analysis was performed of primary and metastatic tumor tissue as well as control tissue. Thereby, 156 single nucleotide variants (SNVs) in 150 genes were identified and amount of mutations per sample ranged from 9–34 (mean 22). The degree of common (0–94%) and private mutations per sample was strongly varying (6–100%). In all patients, copy number variations (CNV) were found and the degree of intratumoral heterogeneity of CNVs corresponded to SNV analysis. DNA methylation analysis of a patient without common SNVs revealed a large overlap of common methylated CpG sites. In conclusion, SI-NET primary and metastatic lesions show a highly varying degree of intratumoral heterogeneity. Driver events might not be detectable with exome analysis only, and further comprehensive studies including whole genome and epigenetic analyses are warranted.
A recent CLOUD (Cosmics Leaving OUtdoor Droplets) chamber study showed that sulfuric acid and dimethylamine produce new aerosols very efficiently and yield particle formation rates that are compatible with boundary layer observations. These previously published new particle formation (NPF) rates are reanalyzed in the present study with an advanced method. The results show that the NPF rates at 1.7 nm are more than a factor of 10 faster than previously published due to earlier approximations in correcting particle measurements made at a larger detection threshold. The revised NPF rates agree almost perfectly with calculated rates from a kinetic aerosol model at different sizes (1.7 and 4.3 nm mobility diameter). In addition, modeled and measured size distributions show good agreement over a wide range of sizes (up to ca. 30 nm). Furthermore, the aerosol model is modified such that evaporation rates for some clusters can be taken into account; these evaporation rates were previously published from a flow tube study. Using this model, the findings from the present study and the flow tube experiment can be brought into good agreement for the high base-to-acid ratios (∼ 100) relevant for this study. This confirms that nucleation proceeds at rates that are compatible with collision-controlled (a.k.a. kinetically controlled) NPF for the conditions during the CLOUD7 experiment (278 K, 38 % relative humidity, sulfuric acid concentration between 1 × 106 and 3 × 107 cm−3, and dimethylamine mixing ratio of ∼ 40 pptv, i.e., 1 × 109 cm−3).
Mannitol is the major compatible solute, next to glutamate, synthesized by the opportunistic human pathogen Acinetobacter baumannii under low water activities. The key enzyme for mannitol biosynthesis, MtlD, was identified. MtlD is highly similar to the bifunctional mannitol‐1‐phosphate dehydrogenase/phosphatase from Acinetobacter baylyi. After deletion of the mtlD gene from A. baumannii ATCC 19606T cells no longer accumulated mannitol and growth was completely impaired at high salt. Addition of glycine betaine restored growth, demonstrating that mannitol is an important compatible solute in the human pathogen. MtlD was heterologously produced and purified. Enzyme activity was strictly salt dependent. Highest stimulation was reached at 600 mmol/L NaCl. Addition of different sodium as well as potassium salts restored activity, with highest stimulations up to 41 U/mg protein by sodium glutamate. In contrast, an increase in osmolarity by addition of sugars did not restore activity. Regulation of mannitol synthesis was also assayed at the transcriptional level. Reporter gene assays revealed that expression of mtlD is strongly dependent on high osmolarity, not discriminating between different salts or sugars. The presence of glycine betaine or its precursor choline repressed promoter activation. These data indicate a dual regulation of mannitol production in A. baumannii, at the transcriptional and the enzymatic level, depending on high osmolarity.
Spatial modelling of malaria cases associated with environmental factors in South Sumatra, Indonesia
(2018)
Background: Malaria, a parasitic infection, is a life-threatening disease in South Sumatra Province, Indonesia. This study aimed to investigate the spatial association between malaria occurrence and environmental risk factors.
Methods: The number of confirmed malaria cases was analysed for the year 2013 from the routine reporting of the Provincial Health Office of South Sumatra. The cases were spread over 436 out of 1613 villages. Six potential ecological predictors of malaria cases were analysed in the different regions using ordinary least square (OLS) and geographically weighted regression (GWR). The global pattern and spatial variability of associations between malaria cases and the selected potential ecological predictors was explored.
Results: The importance of different environmental and geographic parameters for malaria was shown at global and village-level in South Sumatra, Indonesia. The independent variables altitude, distance from forest, and rainfall in global OLS were significantly associated with malaria cases. However, as shown by GWR model and in line with recent reviews, the relationship between malaria and environmental factors in South Sumatra strongly varied spatially in different regions.
Conclusions: A more in-depth understanding of local ecological factors influencing malaria disease as shown in present study may not only be useful for developing sustainable regional malaria control programmes, but can also benefit malaria elimination efforts at village level.
The emerging relapsing fever spirochete Borrelia (B.) miyamotoi is transmitted by ixodid ticks and causes the so-called hard tick-borne relapsing fever or B. miyamotoi disease (BMD). More recently, we identified a surface-exposed molecule, CbiA exhibiting complement binding and inhibitory capacity and rendering spirochetes resistant to complement-mediated lysis. To gain deeper insight into the molecular principles of B. miyamotoi-host interaction, we examined CbiA as a plasmin(ogen) receptor that enables B. miyamotoi to interact with the serine protease plasmin(ogen). Recombinant CbiA was able to bind plasminogen in a dose-dependent fashion. Moreover, lysine residues appear to play a crucial role in the protein-protein interaction as binding of plasminogen was inhibited by the lysine analog tranexamic acid as well as increasing ionic strength. Of relevance, plasminogen bound to CbiA can be converted by urokinase-type plasminogen activator (uPa) to active plasmin which cleaved both, the chromogenic substrate S-2251 and its physiologic substrate fibrinogen. Concerning the involvement of specific amino acids in the interaction with plasminogen, lysine residues located at the C-terminus are frequently involved in the binding as reported for various other plasminogen-interacting proteins of Lyme disease spirochetes. Lysine residues located within the C-terminal domain were substituted with alanine to generate single, double, triple, and quadruple point mutants. However, binding of plasminogen to the mutated CbiA proteins was not affected, suggesting that lysine residues distant from the C-terminus might be involved in the interaction.
The quasi-two-dimensional organic charge-transfer salt κ -(BEDT-TTF) 2 Cu 2 (CN) 3 is one of the prime candidates for a quantum spin-liquid due the strong spin frustration of its anisotropic triangular lattice in combination with its proximity to the Mott transition. Despite intensive investigations of the material’s low-temperature properties, several important questions remain to be answered. Particularly puzzling are the 6 K anomaly and the enigmatic effects observed in magnetic fields. Here we report on low-temperature measurements of lattice effects which were shown to be particularly strongly pronounced in this material (R. S. Manna et al., Phys. Rev. Lett. 2010, 104, 016403)). A special focus of our study lies on sample-to-sample variations of these effects and their implications on the interpretation of experimental data. By investigating overall nine single crystals from two different batches, we can state that there are considerable differences in the size of the second-order phase transition anomaly around 6 K, varying within a factor of 3. In addition, we find field-induced anomalies giving rise to pronounced features in the sample length for two out of these nine crystals for temperatures T< 9 K. We tentatively assign the latter effects to B-induced magnetic clusters suspected to nucleate around crystal imperfections. These B-induced effects are absent for the crystals where the 6 K anomaly is most strongly pronounced. The large lattice effects observed at 6 K are consistent with proposed pairing instabilities of fermionic excitations breaking the lattice symmetry. The strong sample-to-sample variation in the size of the phase transition anomaly suggests that the conversion of the fermions to bosons at the instability is only partial and to some extent influenced by not yet identified sample-specific parameters.
Compact objects - black holes and neutron stars - are fascinating objects, not only for the astrophysicists, but for a wide range of researchers, including astronomers, theoretical physicists, particle and nuclear physicists, condensed matter physicists and arguably for the layman as well.
First theorized in the first part of the twentieth century, for a long time these objects have been considered just exotic ideas or mathematical curiosities. Pulsar were however detected in the late 1960s and readily identified as rotating, radiating neutron stars, while the first candidate black hole, Cygnus X-1, was observed in 1972. Since then the interest in these objects has steadily grown.
The reasons behind this interest are easily understood considering that compact object dwell at the intersection of many different areas of physics, and are ideal laboratories to explore the interplay between these areas.
Black holes, which are purely gravitational objects, are perfectly suited to study the nature of gravity, its manifestations such as gravitational waves, and the differences between various theories of gravity in the regime where they are expected to be most relevant, i.e. the strong field regime. However, just like any massive astrophysical object, black holes are interested by accretion phenomena, which are thought to be the power source of some very bright astrophysical emitters of electromagnetic signals, such as active galactic nuclei or X-ray binaries.
At the same time, black holes exist in a variety of different mass scales, from stellar mass to supermassive black holes billions of times heavier. The latter play a very important and yet not fully understood role in the formation and evolution of galaxies, as well as in shaping the large scale structure of the universe, making them relevant to cosmology as well.
Neutron stars share with black holes the characteristic of being gravitationally dominated systems; but because they are composed of baryon matter, they display a much richer behaviour. It has been realized early on that the matter in neutron star cores reaches extreme densities, exceeding the one in atomic nuclei. This means that neutron stars could provide invaluable information on the behaviour of matter in such extreme conditions (which are impossible to achieve in laboratory experiments), such as details of the nucleonic interaction, the properties of hyperons or of quark-gluon plasmas.
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Diploid transgenic organisms are either hemi- or homozygous. Genetic assays are, therefore, required to identify the genotype. Our AGameOfClones vector concept uses two clearly distinguishable transformation markers embedded in interweaved, but incompatible Lox site pairs. Cre-mediated recombination leads to hemizygous individuals that carry only one marker. In the following generation, heterozygous descendants are identified by the presence of both markers and produce homozygous progeny that are selected by the lack of one marker. We prove our concept in Tribolium castaneum by systematically creating multiple functional homozygous transgenic lines suitable for long-term fluorescence live imaging. Our approach saves resources and simplifies transgenic organism handling. Since the concept relies on the universal Cre-Lox system, it is expected to work in all diploid model organisms, for example, insects, zebrafish, rodents and plants. With appropriate adaptions, it can be used in knock-out assays to preselect homozygous individuals and thus minimize the number of wasted animals.
The mission of the Compressed Baryonic Matter (CBM) experiment is to investigate the phase diagram of strongly interacting matter in the region of high net-baryon densities and moderate temperatures. According to various transport models, matter densities of more than 5 times saturation density can be reached in collisions between gold nuclei at beam energies between 5 and 11 GeV per nucleon, which will be available at FAIR. The core detector of the CBM experiment is the Silicon Tracking System (STS), which is used to measure the tracks of up to 700 particles per collision with high efficiency (>95%) and good momentum resolution (<1.5%). The technological and experimental challenge is to realize a detector system with very low material budget, in order to reduce multiple scattering of the particles, and a free-streaming data readout chain, in order to achieve reaction rates up to 10 MHz together with an online event reconstruction and selection.
The STS comprises 8 tracking stations positioned between 30 cm and 100 cm downstream the target inside a magnetic field, covering polar emission angles up to 25 degrees. A station consists of vertical structures with increasing number (between 8 and 16, depending on station number), each structure carrying between 2 and 10 double-sided microstrip silicon sensors, which are connected through low-mass microcables to the readout electronics placed at the detector periphery outside the active detector area.
The work presented in this thesis focuses on the detector performance simulation and local hit pattern reconstruction in the STS. For efficient detector design and reconstruction performance, a reliable detector response model is of utmost importance. Within this work, a realistic detector response model was designed and implemented in the CBM software framework. The model includes non-uniform energy loss of an incident particle within a sensor, electric field of a planar p-n junction, Lorentz shift of the charge carriers, their diffusion, and the influence of parasitic capacitances. The developed model has been verified with experimental data from detector tests in a relativistic proton beam. Cluster size distributions at different beam incident angles are sensitive to charge sharing effects and were chosen as an observable for the verification. Taking into account parasitic capacitances further improves the agreement with measured data.
Using the developed detector response model, the cluster position finding algorithm was improved. For two-strip clusters, a new, unbiased algorithm has been developed, which gives smaller residuals than the Centre-Of-Gravity algorithm. For larger clusters, the head-tail algorithm is used as the default one. For an estimate of the track parameters, the Kalman Filter based track fit requires not only hit positions but their uncertainties as an input. A new analytic method to estimate the hit position errors has been designed in this work. It requires as input neither measured spatial resolution nor information about an incident particle track. The method includes all the sources of uncertainties independently, namely: the cluster position finding algorithm itself, the non-uniform energy loss of incident particles, the electronics noise, and the discretisation of charge in the readout chip.
The verification with simulations shows improvements in hit and track pull distributions as well as x²-distributions in comparison to the previous simple approach. The analytic method improves the track parameters reconstruction by 5-10%.
Several STS module prototypes have been tested in a relativistic proton beam. A signal to-noise ratio was obtained at the level of 10-15 for modules made of 30 cm long microcable and of either one or two 6.2 x 6.2 cm² CiS sensors.
First simulations have shown that this signal-to-noise ratio is sufficient to reach the required efficiency and momentum resolution. The high-radiation environment of CBM operation will deteriorate the sensor performance. Radiation hardness of sensors has been studied in the beam with sensors irradiated to 2 x 10[hoch 14] 1MeV [neq/cm²], twice the lifetime dose expected for CBM operation. Charge collection efficiency drops by 17-25%, and simultaneously noise levels increase 1.5-1.75 times. The simulations show that if all sensors in the STS setup are exposed to such a fluence uniformly, the track reconstruction efficiency drops from 95.5% to 93.2% and the momentum resolution degrades from 1.6% to 1.7%.
Rationale: Classic histology is the gold standard for vascular network imaging and analysis. The method however is laborious and prone to artefacts. Here, the suitability of ultramicroscopy (UM) and micro-computed tomography (CT) was studied to establish potential alternatives to histology.
Methods: The vasculature of murine organs (kidney, heart and atherosclerotic carotid arteries) was visualized using conventional 2D microscopy, 3D light sheet ultramicroscopy (UM) and micro-CT. Moreover, spheroid-based human endothelial cell vessel formation in mice was quantified. Fluorescently labeled Isolectin GS-IB4 A647 was used for in vivo labeling of vasculature for UM analysis, and analyses were performed ex vivo after sample preparation. For CT imaging, animals were perfused postmortem with radiopaque contrast agent.
Results: Using UM imaging, 3D vascular network information could be obtained in samples of animals receiving in vivo injection of the fluorescently labeled Isolectin GS-IB4. Resolution was sufficient to measure single endothelial cell integration into capillaries in the spheroid-based matrigel plug assay. Because of the selective staining of the endothelium, imaging of larger vessels yielded less favorable results. Using micro-CT or even nano-CT, imaging of capillaries was impossible due to insufficient X-ray absorption and thus insufficient signal-to-noise ratio. Identification of lumen in murine arteries using micro-CT was in contrast superior to UM.
Conclusion: UM and micro-CT are two complementary techniques. Whereas UM is ideal for imaging and especially quantifying capillary networks and arterioles, larger vascular structures are easier and faster to quantify and visualize using micro-CT. 3D information of both techniques is superior to 2D histology. UM and micro-CT together may open a new field of clinical pathology diagnosis.