Imaging intact human organs with local resolution of cellular structures using hierarchical phase-contrast tomography.

Imaging intact human organs from the organ to the cellular scale in three dimensions is a goal of biomedical imaging. To meet this challenge, we developed hierarchical phase-contrast tomography (HiP-CT), an X-ray phase propagation technique using the European Synchrotron Radiation Facility (ESRF)'s Extremely Brilliant Source (EBS). The spatial coherence of the ESRF-EBS combined with our beamline equipment, sample preparation and scanning developments enabled us to perform non-destructive, three-dimensional (3D) scans with hierarchically increasing resolution at any location in whole human organs. We applied HiP-CT to image five intact human organ types: brain, lung, heart, kidney and spleen. HiP-CT provided a structural overview of each whole organ followed by multiple higher-resolution volumes of interest, capturing organotypic functional units and certain individual specialized cells within intact human organs. We demonstrate the potential applications of HiP-CT through quantification and morphometry of glomeruli in an intact human kidney and identification of regional changes in the tissue architecture in a lung from a deceased donor with coronavirus disease 2019 (COVID-19).

Altered DNA methylation at age-associated CpG sites in children with growth disorders: impact on age estimation?

Age estimation based on DNA methylation (DNAm) can be applied to children, adolescents and adults, but many CG dinucleotides (CpGs) exhibit different kinetics of age-associated DNAm across these age ranges. Furthermore, it is still unclear how growth disorders impact epigenetic age predictions, and this may be particularly relevant for a forensic application. In this study, we analyzed buccal mucosa samples from 95 healthy children and 104 children with different growth disorders. DNAm was analysed by pyrosequencing for 22 CpGs in the genes PDE4C, ELOVL2, RPA2, EDARADD and DDO. The relationship between DNAm and age in healthy children was tested by Spearman's rank correlation. Differences in DNAm between the groups "healthy children" and the (sub-)groups of children with growth disorders were tested by ANCOVA. Models for age estimation were trained (1) based on the data from 11 CpGs with a close correlation between DNAm and age (R ≥ 0.75) and (2) on five CpGs that also did not present significant differences in DNAm between healthy and diseased children. Statistical analysis revealed significant differences between the healthy group and the group with growth disorders (11 CpGs), the subgroup with a short stature (12 CpGs) and the non-short stature subgroup (three CpGs). The results are in line with the assumption of an epigenetic regulation of height-influencing genes. Age predictors trained on 11 CpGs with high correlations between DNAm and age revealed higher mean absolute errors (MAEs) in the group of growth disorders (mean MAE 2.21 years versus MAE 1.79 in the healthy group) as well as in the short stature (sub-)groups; furthermore, there was a clear tendency for overestimation of ages in all growth disorder groups (mean age deviations: total growth disorder group 1.85 years, short stature group 1.99 years). Age estimates on samples from children with growth disorders were more precise when using a model containing only the five CpGs that did not present significant differences in DNAm between healthy and diseased children (mean age deviations: total growth disorder group 1.45 years, short stature group 1.66 years). The results suggest that CpGs in genes involved in processes relevant for growth and development should be avoided in age prediction models for children since they may be sensitive for alterations in the DNAm pattern in cases of growth disorders.

Evidence for differences in DNA methylation between Germans and Japanese.

As a contribution to the discussion about the possible effects of ethnicity/ancestry on age estimation based on DNA methylation (DNAm) patterns, we directly compared age-associated DNAm in German and Japanese donors in one laboratory under identical conditions. DNAm was analyzed by pyrosequencing for 22 CpG sites (CpGs) in the genes PDE4C, RPA2, ELOVL2, DDO, and EDARADD in buccal mucosa samples from German and Japanese donors (N = 368 and N = 89, respectively).Twenty of these CpGs revealed a very high correlation with age and were subsequently tested for differences between German and Japanese donors aged between 10 and 65 years (N = 287 and N = 83, respectively). ANCOVA was performed by testing the Japanese samples against age- and sex-matched German subsamples (N = 83 each; extracted 500 times from the German total sample). The median p values suggest a strong evidence for significant differences (p < 0.05) at least for two CpGs (EDARADD, CpG 2, and PDE4C, CpG 2) and no differences for 11 CpGs (p > 0.3).Age prediction models based on DNAm data from all 20 CpGs from German training data did not reveal relevant differences between the Japanese test samples and German subsamples. Obviously, the high number of included "robust CpGs" prevented relevant effects of differences in DNAm at two CpGs.Nevertheless, the presented data demonstrates the need for further research regarding the impact of confounding factors on DNAm in the context of ethnicity/ancestry to ensure a high quality of age estimation. One approach may be the search for "robust" CpG markers-which requires the targeted investigation of different populations, at best by collaborative research with coordinated research strategies.

[COVID-19-induced coagulopathy and thrombosis manifestations]. / COVID-19-induzierte Koagulopathien und thromboembolische Manifestationen.

CLINICAL ISSUE: Clinically, COVID-19 (coronavirus disease 2019) is increasingly seen as a systemic disease associated with multiorgan involvement through a hypercoagulatory condition in the sense of vasculopathy. STANDARD TREATMENT: Treatment with antiplatelet drugs or heparins appears to be indicated. The current evidence, at least for acetylsalicylic acid (ASA), is lacking. DIAGNOSTIC WORK-UP: Corresponding to the significant proportion of primarily microstructural vascular changes, the radiological diagnosis showed not only macrovascular pathologies, but also diffuse perfusion disorders. PERFORMANCE: Regional hypoperfusion in the lungs can be detected with and without pulmonary arterial embolism. Similar findings can be found in almost all organ systems. PRACTICAL RECOMMENDATIONS: A therapeutic intervention using low molecular weight heparins in hospitalized patients in situation-adapted dosage is indicated and is discussed in detail. In the detection of micro- and macrovascular thrombosis in the context of COVID-19, extended radiological diagnostics play a central role and are the basis of adapted therapy and secondary prevention.

Photon-counting detectors in computed tomography: from quantum physics to clinical practice.

Over the last decade, a fundamentally new type of computed tomography (CT) detectors has proved its superior capabilities in both physical and preclinical evaluations and is now approaching the stage of clinical practice. These detectors are able to discriminate single photons and quantify their energy and are hence called photon-counting detectors. Among the promising benefits of this technology are improved radiation dose efficiency, increased contrast-to-noise ratio, reduced metal artifacts, improved spatial resolution, simultaneous multi-energy acquisitions, and the prospect of multi-phase imaging within a single acquisition using multiple contrast agents. Taking the conventional energy-integrating detectors as a reference, the authors demonstrate the technical principles of this new technology and provide phantom and patient images acquired by a whole-body photon-counting CT. These images serve as a basis for discussing the potential future of clinical CT.

[Microvascular changes in COVID-19]. / Mikrovaskuläre Veränderungen bei COVID-19.

BACKGROUND: Clinically, coronavirus disease 2019 (COVID-19) is associated with a wide range of symptoms, which can range from mild complaints of an upper respiratory infection to life-threatening hypoxic respiratory insufficiency and multiorgan failure. OBJECTIVE: The initially identified pulmonary damage patterns, such as diffuse alveolar damage in acute lung failure, are accompanied by new findings that draw a more complex scenario. These include microvascular involvement and a wide range of associated pathologies of multiple organ systems. A back-scaling of microstructural vascular changes is possible via targeted correlation of pathological autopsy results with radiological imaging. MATERIAL AND METHODS: Radiological and pathological correlation as well as microradiological imaging to investigate microvascular involvement in fatal COVID-19. RESULTS: The cases of two COVID-19 patients are presented. Patient 1 showed a relative hypoperfusion in lung regions that did not have typical COVID-19 infiltrates; the targeted post-mortem correlation also showed subtle signs of microvascular damage even in these lung sections. Patient 2 showed both radiologically and pathologically advanced typical COVID-19 destruction of lung structures and the case illustrates the damage patterns of the blood-air barrier. The perfusion deficit of the intestinal wall shown in computed tomography of patient 2 could not ultimately clearly be microscopically attributed to intestinal microvascular damage. CONCLUSION: In addition to microvascular thrombosis, our results indicate a functional pulmonary vasodysregulation as part of the pathophysiology during the vascular phase of COVID-19. The clinical relevance of autopsies and the integration of radiological imaging findings into histopathological injury patterns must be emphasized for a better understanding of COVID-19.

[Temporary hyposmia in COVID-19 patients]. / Temporäre Hyposmie bei COVID-19-Patienten.

BACKGROUND: This is a report on the high incidence of olfactory dysfunction in COVID-19 patients in the first cohort of COVID-19 patients in Germany (Webasto cluster). METHODS: Loss of sense of smell and/or taste was reported by 26 of 63 COVID-19 patients (41%), whereas only 31% of the patients experiencing hyposmia had simultaneous symptoms of rhinitis. Smell tests were performed in 14 of these patients and taste tests in 10. The measurements were conducted in a patient care setting in an early COVID-19 cohort. RESULTS: An olfactory disorder was present in 10/14 patients, before as well as after nasal decongestion. In 2 of these patients, hyposmia was the leading or only symptom of SARS-CoV­2 infection. All tested patients reported recovery of smell and/or taste within 8 to 23 days. CONCLUSION: The data imply that a) COVID-19 can lead to hyposmia in a relevant number of patients, the incidence was approximately 30% in this cohort; b) in most cases, the olfactory disturbance was not associated with nasal obstruction, thus indicating a possible neurogenic origin; and c) the olfactory disorder largely resolved within 1-3 weeks after the onset of COVID-19 symptoms. There were no indications of an increased incidence of dysgeusia. These early data may help in the interpretation of COVID-19-associated hyposmia as well as in the counseling of patients, given the temporary nature of hyposmia observed in this study. Furthermore, according to the current experience, hyposmia without rhinitic obstruction can be the leading or even the only symptom of a SARS-CoV­2 infection.

Head Loss in Thin-Walled Drip Tapes with Continuous Labyrinth.

Thin-walled drip tapes with continuous labyrinth have been used for irrigation of vegetables and other short-cycle crops, especially due to their low cost. The continuous labyrinths welded into the pipe inner wall affect the head loss along such emitting pipes. In addition, the flow cross section of thin-walled pipes may change due to the effects of the operating pressure, which also has consequences for the head loss. The objective of this work was to investigate experimentally the friction factor and the head loss on thin-walled drip tapes with continuous labyrinths operated under various pressures. Two models of commercial thin-walled drip tapes with continuous labyrinths were evaluated. Nonperforated samples were used to determine the head-loss equations. The equations were adjusted as a function of flow rate and pressure head at the pipe inlet. Alternatively, the diameter in the Darcy-Weisbach equation was adjusted as a function of the pressure head by a power-law model. The possibility of using a mean diameter in the Darcy-Weisbach equation was also analyzed. Experimental investigation indicated that the friction factor in the Darcy-Weisbach equation can be accurately described using a power-law model, like the Blasius equation, but characterized by a coefficient a=0.3442 for the Turbo Tape and a=0.3225 for the Silver Tape. The obtained values of a are larger than those generally used and available in the literature. The influence of the operating pressure on the pipe diameter can be neglected for the purpose of calculating the head loss. The two approaches, considering the variation of the diameter with the pressure head and considering an optimum average diameter for the calculation of head loss by the Darcy-Weisbach equation, produce similar results, allowing accurate prediction of head loss. Evaluating the proposed mathematical models, 95% of predictions presented relative errors of head loss smaller than 5%. For the Turbo Tape, the optimum diameter for the purpose of calculating the head loss is 16.01 mm, which is very close to the value indicated by its manufacturer (15.9 mm). For the Silver Drip, the optimum diameter is 15.71 mm, while the manufacturer gives a value of 16.22 mm, which produces considerable error in the calculation of head loss.

Joint Sentinel-1 and SMAP data assimilation to improve soil moisture estimates.

SMAP (Soil Moisture Active and Passive) radiometer observations at ~40 km resolution are routinely assimilated into the NASA Catchment Land Surface Model to generate the 9-km SMAP Level-4 Soil Moisture product. This study demonstrates that adding high-resolution radar observations from Sentinel-1 to the SMAP assimilation can increase the spatio-temporal accuracy of soil moisture estimates. Radar observations were assimilated either separately from or simultaneously with radiometer observations. Assimilation impact was assessed by comparing 3-hourly, 9-km surface and root-zone soil moisture simulations with in situ measurements from 9-km SMAP core validation sites and sparse networks, from May 2015 to December 2016. The Sentinel-1 assimilation consistently improved surface soil moisture, whereas root-zone impacts were mostly neutral. Relatively larger improvements were obtained from SMAP assimilation. The joint assimilation of SMAP and Sentinel-1 observations performed best, demonstrating the complementary value of radar and radiometer observations.

Survival and tissue maintenance of an implant with a sloped configurated shoulder in the posterior mandible-a prospective multicenter study.

AIM: Clinical studies evaluating the influence of the implant design on the preservation of peri-implant keratinized mucosa are rare. The aim of this prospective multicenter study was to investigate the survival, and soft and hard tissue maintenance of an implant with a sloped shoulder configuration, when placed in the posterior mandible. MATERIAL AND METHODS: In this study, 24 centers participated and 184 patients receiving 238 implants (OsseoSpeed™ Profile TX implants) were included. Clinical assessments of soft tissue parameters were performed before implant placement, immediately after implant placement, at prosthetic delivery and at 6, 12 and 24 months after implant placement and marginal bone adaptation was examined. RESULTS: After an average time in situ of 28.7 ± 4.7 months (2.4 ± 0.4 years), the survival rate was 99.2%. Analysis of the peri-implant soft tissues during follow-up showed a slight but significant increase in peri-implant keratinized mucosa width after 2 years (P < 0.001). All patients with reduced peri-implant keratinized mucosa width of ≤ 2 mm at postoperative examination (n = 95) showed a pronounced and statistically significant increase in the peri-implant keratinized mucosa width over time (P < 0.001). After a mean follow-up of 20.7 ± 8 months (1.7 ± 0.7 years), mean inter-proximal marginal bone loss was 0.30 ± 0.6 mm, indicating high bone stability around the sloped implant neck. CONCLUSION: These results indicate that sloped configurated implants have a high survival rate after 2 years in function. The sloped implant shoulder configuration helps to support the hard and soft tissue around the implant neck and supports the regain of a physiological peri-implant keratinized mucosa in patients with compromised peri-implant soft tissue conditions (Clinicaltrials.gov: NCT01400321).

Three-dimensional image analytical detection of intussusceptive pillars in murine lung.

A variety of diseases can lead to loss of lung tissue. Currently, this can be treated only symptomatically. In mice, a complete compensatory lung growth within 21 days after resection of the left lung can be observed. Understanding and transferring this concept of compensatory lung growth to humans would greatly improve therapeutic options. Lung growth is always accompanied by a process called angiogenesis forming new capillary blood vessels from preexisting ones. Among the processes during lung growth, the formation of transluminal tissue pillars within the capillary vessels (intussusceptive pillars) is observed. Therefore, pillars can be understood as an indicator for active angiogenesis and microvascular remodelling. Thus, their detection is very valuable when aiming at characterization of compensatory lung growth. In a vascular corrosion cast, these pillars appear as small holes that pierce the vessels. So far, pillars were detected visually only based on 2D images. Our approach relies on high-resolution synchrotron microcomputed tomographic images. With a voxel size of 370 nm we exploit the spatial information provided by this imaging technique and present the first algorithm to semiautomatically detect intussusceptive pillars. An at least semiautomatic detection is essential in lung research, as manual pillar detection is not feasible due to the complexity and size of the 3D structure. Using our algorithm, several thousands of pillars can be detected and subsequently analysed, e.g. regarding their spatial arrangement, size and shape with an acceptable amount of human interaction. In this paper, we apply our novel pillar detection algorithm to compute pillar densities of different specimens. These are prepared such that they show different growing states. Comparing the corresponding pillar densities allows to investigate lung growth over time.

Synchrotron-based X-ray tomographic microscopy for visualization of three-dimensional collagen matrices.

INTRODUCTION: Three-dimensional collagen matrices (3D-CMs) may be visualized by cumbersome reconstructions of serial sections. We report here on the method of synchrotron-based X-ray tomographic microscopy (SRXTM) to image 3D-CMs in native tissue probes. MATERIAL AND METHODS: SRXTM of 3D-CMs (mucoderm®, mucograft®) was performed at the TOMCAT beamline of the Swiss Light Source (SLS) at the Paul Scherrer Institute (Villigen, Switzerland). RESULTS: SRXTM combines the advantages of high-resolution scanning electron microscopy (SEM) imaging with the low-resolution reconstructions of micro-CT (µCT) imaging. It may be used to non-destructively visualize and analyze structures within the 3D-CMs without the need of serial sectioning and reconstruction. CONCLUSION: High-resolution SRXTM is a useful tool in analyzing the topology and morphometry of structures in 3D-CMs. The outcome justifies the efforts in sophisticated data processing. CLINICAL RELEVANCE: SRXTM may help to understand the clinical characteristics of 3D-CMs in more detail.

Discriminating metastasised from non-metastasised seminoma based on transcriptional changes in primary tumours using NGS.

BACKGROUND: We aimed to better discriminate (occult) metastasised from non-metastasised seminoma based on transcriptional changes of small RNAs in the primary tumour. METHODS: Total RNAs including small RNAs were isolated from five testicular tumours of each, lymphogenic, occult and non-metastasised patients. Next-generation sequencing (SOLID, Life Technologies) was used to examine transcriptional changes. Small RNAs showing ⩾50 reads and a significant ⩾2-fold difference using non-metastasised tumours as the reference group were examined in univariate logistic regression analysis and combinations of two small RNAs were further examined using support vector machines. RESULTS: On average, 1.3 × 10(7), 1.4 × 10(7) and 1.7 × 10(7) small RNA reads were detectable in non-metastasised, occult and lymphogenic metastasised seminoma, respectively, of which 30-32% remained after trimming. Between 59 and 68% represented annotated reads and between 8.6 and 11% were annotated small RNA tags. Of them, 137 small RNAs showed>50 reads and a two-fold difference to the reference. In univariate analysis, 32-38 small RNAs significantly discriminated lymphogenic/occult from non-metastasised seminoma, and among these different comparisons, it were the same small RNAs in 51-88%. Many combinations of two of these small RNAs allowed a complete discrimination of metastasised from non-metastasised seminoma irrespective of the metastasis subtype. CONCLUSIONS: Metastasised and non-metastasised seminoma can be completely discriminated with a combination of two small RNAs.

Prediction of metastatic status in non-seminomatous testicular cancer.

PURPOSE: To examine the significance of 90 biomarkers for predicting metastatic status in non-seminomatous germ cell tumors (NSGCT). By predicting metastatic status, it may be possible to eliminate unnecessary therapeutic or diagnostic efforts. MATERIALS AND METHODS: We investigated 552 males who were diagnosed with non-metastatic (n = 273) and metastatic (n = 279) NSGCT between 2000 and 2011. The sample included cancers of different histologies: embryonal cell carcinoma (n = 131), teratoma (n = 55), and mixed histology (n = 366). We collected and analyzed more than 90 parameters via logistic regression: demographic characteristics, medical history, histopathological parameters, and levels of tumor markers and hormones. RESULTS: Testis histology (p = 0.004), clinical symptoms (p = 0.0005), tumor length (p = 0.005), infiltration of the rete testis (p = 0.008), invasion of lymphatic (pL1) and blood vessels (pV1) (p < 0.0001), and levels of enzymes such as LDH, ßHCG, AFP, and FSH (p values as small as <0.0001) were associated with metastatic status. With one model, we identified 14 out of 76 (18.4 %) metastatic NSGCT cases with 93-100 % certainty (positive predictive value) at 99 % specificity by the peripheral blood levels of LDH (day of operation) in combination with FSH measurements (1 day after operation). A second model included pV, tumor length, and FSH (1 day after operation). It identified 25 out of 90 (27.8 %) non-metastatic NSGCT with approximately 90 % certainty (negative predictive value) at 94-98 % sensitivity. CONCLUSIONS: No single parameter was able to discriminate metastatic from non-metastatic NSGCT, but combinations of parameters in two predictive models accurately identified the metastatic status in 23 % of the cases in our sample.

[Tetraplegia, resuscitation and epileptic seizures after partial colon resection in a 41-year-old woman]. / Tetraplegie, Reanimation und Krampfanfälle nach Kolonteilresektion bei einer 41-Jährigen.

A 41-year-old woman, suffering from continuous abdominal pain, only presented a non-specific inflammation of the whole colon and an unclaryfied hyponatriaemia; in spite of the only doubtful explanation by an enormous elongation of the colon, it was partially resected. Thereafter, the patient's decline, hypaesthesia, areflexia and tetraparesis required intensive care. Despite immunoglobulin therapy, assuming a Guillain-Barré syndrome, the patient needed resuscitation, followed by signs of severe hypoxia (high level of neuron-specific enolase, hippocampal lesions). The abdominal pain, hyponatriaemia, persistent tachycardia, sensory deficits, tetraplegia, circulation arrest, later epileptic seizures and unusual urine color were finally explained by an acute intermittent porphyria (AIP). Although the symptoms were classic, the disease was recognized only very late. Indeed, it is so rare that most physicians will never be confronted with an AIP or only once or twice.

The search for biomarkers of metastatic seminoma.

PURPOSE: We screened 90 potential parameters as biomarkers of metastatic seminoma to facilitate detection and eliminate unnecessary therapeutic or diagnostic efforts. MATERIALS AND METHODS: A total of 527 men with pure seminoma (diagnosed 2000 to 2011) were followed during therapy. More than 90 demographic/anamnestic (eg age, height, weight) histopathological parameters (testicular/tumor size, testicular intraepithelial neoplasia) and levels of tumor markers (eg α-fetoprotein, ß-human chorionic gonadotropin, lactate dehydrogenase) in peripheral blood and testicular vein were collected for analysis via logistic regression. Previously described risk factors (tumors larger than 4 cm, infiltration of rete testis) were assessed separately. RESULTS: Established parameters such as tumor length (p = 0.0003), involvement of lymphatic (p <0.0001) or vascular channels (p = 0.0009), extent of primary tumor (p <0.0001) and infiltration of the tunica albuginea (p = 0.02) as well as new biomarkers such as absence of testicular intraepithelial neoplasia in tumor bearing testis (p = 0.03), testicular volume (p = 0.04) and tumor volume (p = 0.02) showed a significant association with metastatic disease. This association was also true of lactate dehydrogenase, human chorionic gonadotropin and α-fetoprotein (p <0.0001 at maximum). However, the discriminatory capacity of these biomarkers (concordance or ROC area) did not exceed 65% when examined alone or in combination, and higher values (up to 80%) were detected for enzyme levels. A subset of metastatic seminoma (2% to 27%) was detectable with high accuracy (positive predictive value 92% to 100%) based on enzyme measurements (p <0.0006). CONCLUSIONS: New biomarkers of metastatic seminoma were identified and previously described risk factors were validated. Further prospective studies of these novel parameters are warranted to verify our findings and to explore a potential use for detecting occult metastases.

High-precision x-ray polarimetry.

The polarization purity of 6.457- and 12.914-keV x rays has been improved to the level of 2.4×10(-10) and 5.7×10(-10). The polarizers are channel-cut silicon crystals using six 90° reflections. Their performance and possible applications are demonstrated in the measurement of the optical activity of a sucrose solution.

Detection of intracranial circulatory arrest in brain death using cranial CT-angiography.

BACKGROUND AND PURPOSE: Computed tomographic-angiography (CT-A) is becoming more accepted in detecting intracranial circulatory arrest in brain death (BD). An international consensus about the use and the parameters of this technique is currently not established. We examined intracranial contrast enhancement in CT-A after clinically confirmed BD, compared the results with electroencephalography (EEG) and Transcranial Doppler Ultrasonography (TCD) findings and developed a commonly applicable CT-A protocol. METHODS: Prospective, monocentric study between April 2008 and October 2011. EEG, TCD and CT-A were performed in 63 patients aged between 18 and 88 years (mean, 55 years) who fulfilled clinical criteria of BD. Evaluation of opacification of cerebral vascular territories in CT-A was performed in arterial as well as in venous scanning series by a neuroradiologist and a neurointensivist/neurosurgeon together. RESULTS: CT-A demonstrated a 95% sensitivity in detecting intracranial circulatory arrest when analysing arterial scanning series. We never observed venous blood return in internal cerebral veins. In three cases, BD confirmation by EEG failed because of artefacts. Confirmation of BD by TCD failed in two cases because of absent temporal window. In three cases, TCD demonstrated residual blood flow. CONCLUSION: CT-A is easily accessible in almost every hospital, offers a high spatio-temporal resolution, is operator independent and inexpensive. The results of CT-A are comparable to other established brain perfusion techniques in BD. An international consensus should be established to ascertain consistent parameters similar to fixed guidelines for other ancillary procedures to determine BD in order to prevent different scanning and evaluation protocols for detecting intracranial circulatory arrest.

Carbonic anhydrase immobilized on hollow fiber membranes using glutaraldehyde activated chitosan for artificial lung applications.

Extracorporeal CO2 removal from circulating blood is a promising therapeutic modality for the treatment of acute respiratory failure. The enzyme carbonic anhydrase accelerates CO2 removal within gas exchange devices by locally catalyzing HCO3 (-) into gaseous CO2 within the blood. In this work, we covalently immobilized carbonic anhydrase on the surface of polypropylene hollow fiber membranes using glutaraldehyde activated chitosan tethering to amplify the density of reactive amine functional groups for enzyme immobilization. XPS and a colorimetric amine assay confirmed higher amine densities on the chitosan coated fiber compared to control fiber. Chitosan/CA coated fibers exhibited accelerated CO2 removal in scaled-down gas exchange devices in buffer and blood (115% enhancement vs. control, 37% enhancement vs. control, respectively). Carbonic anhydrase immobilized directly on hollow fiber membranes without chitosan tethering resulted in no enhancement in CO2 removal. Additionally, fibers coated with chitosan/carbonic anhydrase demonstrated reduced platelet adhesion when exposed to blood compared to control and heparin coated fibers.

[Results of preclinically placed thoracic drainages]. / Outcome-Analyse präklinisch gelegter Thoraxdränagen.

BACKGROUND: Thorax injuries are to be found in approximately 78 % amongst all victims of accidents. Moreover they implicate an increase in mortality rate. Consequently an adequate contemporary treatment has to begin preclinically, even if the conditions are less comfortable than in a clinical setting. Emergency doctors need to be familiar with the placement of chest tubes. METHODS: From 01.01.2007 to 31.12.2010 emergency doctors of the rescue helicopter site Christoph 20 had to place chest tubes directly at the scene of an accident in 49 patients. These patients were now reidentified and their clinical course reevaluated. By means of apparative diagnostics it was possible to analyse the location of the tips of the tubes. A comparison of the patient outcome versus the quality of preclinical thoracic drainage could be made. RESULTS: The preclinical placement of a chest tube became necessary mainly because of a blunt thoracic trauma. This was predominantly related to victims of traffic accidents, whereas male victims clearly dominated. 42 of those patients received further treatment at the Klinikum Bayreuth, enabling an analysis of the tube locations by CT scans. Six patients had been drained on both sides, contributing to the 48 tube tips that could be examined concerning their location. Of the 48 chest tubes 46 had been placed from a lateral approach. The ventral access according to Monaldi had only been chosen in two cases. Altogether nine incorrect placements, mainly within the right interlobe gap, were detected. CONCLUSION: The study collective showed a significant preference to the lateral approach when placing a chest tube at the emergency scene of an accident. In total a prevalence of 19 % incorrect placements could be revealed, meaning the chest tube had either been placed within the lung parenchyma, the interlobe gap or extrathoracically. Concerning the patient outcome no statistically significant difference regarding the clinical course after incorrect chest tube placement could be identified. The omission of an indicated preclinical thoracic drainge is certainly a more serious error than its incorrect placement with more serious consequences.