Whole-Mount Immunofluorescence Staining, Confocal Imaging and 3D Reconstruction of the Sinoatrial and Atrioventricular Node in the Mouse

The electrical signal physiologically generated by pacemaker cells in the sinoatrial node (SAN) is conducted through the conduction system, which includes the atrioventricular node (AVN), to allow excitation and contraction of the whole heart. Any dysfunction of either SAN or AVN results in arrhythmias, indicating their fundamental role in electrophysiology and arrhythmogenesis. Mouse models are widely used in arrhythmia research, but the specific investigation of SAN and AVN remains challenging. The SAN is located at the junction of the crista terminalis with the superior vena cava and AVN is located at the apex of the triangle of Koch, formed by the orifice of the coronary sinus, the tricuspid annulus, and the tendon of Todaro. However, due to the small size, visualization by conventional histology remains challenging and it does not allow the study of SAN and AVN within their 3D environment. Here we describe a whole-mount immunofluorescence approach that allows the local visualization of labelled mouse SAN and AVN. Whole-mount immunofluorescence staining is intended for smaller sections of tissue without the need for manual sectioning. To this purpose, the mouse heart is dissected, with unwanted tissue removed, followed by fixation, permeabilization and blocking. Cells of the conduction system within SAN and AVN are then stained with an anti-HCN4 antibody. Confocal laser scanning microscopy and image processing allow differentiation between nodal cells and working cardiomyocytes, and to clearly localize SAN and AVN. Furthermore, additional antibodies can be combined to label other cell types as well, such as nerve fibers. Compared to conventional immunohistology, whole-mount immunofluorescence staining preserves the anatomical integrity of the cardiac conduction system, thus allowing the investigation of AVN; especially so into their anatomy and interactions with the surrounding working myocardium and non-myocyte cells.

Technical note: Validation of an in-house bovine serum enzyme immunoassay for progesterone measurement

Measuring circulating progesterone (P4) of dairy cows is a key component of many research studies dealing with basic and applied reproduction physiology. The gold standard in dairy cows for the measurement of P4 in serum is radioimmunoassay (RIA), but it generates radioactive waste and requires licensed facilities. The purpose of this study was to develop and validate an in-house competitive enzyme immunoassay (EIA) to measure the P4 concentration in serum of dairy cattle. The secondary objective was to validate a commercial EIA. In the present study, a competitive EIA was developed using commercially available antibodies and conjugates. Ninety-six well microtiter plates were coated with the secondary antibody and incubated overnight. Following a washing step, the wells were blocked using the primary antibody. Serum samples were prepared by first extracting P4 using petroleum ether, then diluted in working conjugate solution. Samples were pipetted into the coated and blocked plates, then the matching HRP conjugate label (P4-3-HRP, East Coast Bio, North Berwick, ME) was added. The plates were incubated for 2 h, then washed. The substrate solution was added, and the plate was incubated up to 1 h at room temperature in the dark until a blue color had developed. A stop solution was added, and the optical density measured on a microplate reader was set at 450 nm. The binding proportion was calculated by a visible spectrum absorbance reader, and the amount of P4 was calculated using a log-logit regression line. The commercial EIA was executed as suggested by the manufacturer. The validation of the in-house EIA was done by calculating the inter- and intraassay coefficients of variation (CV) and evaluating the parallelism of diluted samples. The results from the in-house and commercial EIA were also compared with the ones from the RIA graphically (scatterplots and Bland-Altman plots) and statistically, using the Spearman correlation coefficient (r) and the Cohen's kappa statistics using a threshold of 1.0 ng/mL (κ). For the in-house EIA, the intraassay CV were all <10%, but the interassay for samples with small and large P4 concentration had CV of 12.5 and 11.0%, respectively. The correlations between the results from the EIA and the RIA were strong (in-house: r = 0.90; commercial: r = 0.83). At small concentrations (<1.0 ng/mL), however, the correlation with the gold standard was weak (in-house: r = 0.27; commercial: r = 0.14). This was likely due to the lack of accuracy at small concentrations, also shown by the absence of parallelism in samples ≤0.4 ng/mL. In conclusion, results from both the in-house and commercial EIA strongly correlated with the gold standard, but less so at smaller concentrations. The in-house EIA offers good accuracy to measure P4 in samples with a concentration >0.4 ng/mL, and a perfect agreement with RIA using a threshold of 1.0 ng/mL.

[Consent management and workflows for cross-sectoral patient records and teleconsultations]

Cross-enterprise electronic patient records are a key element in the design of interoperable medical care networks and process chains. However, the different requirements concerning type, performance and quality assurance of available communication services within the different healthcare sectors still require that the hospitals participate in various secure communication networks which have to be bridged for cross-sectoral communication. Cross-institutional pathways for telemedicine, however, can be mapped both within and across sectoral boundaries via automated process chains using the IHE (Integrating the Healthcare Enterprise) defined integration profile CrossEnterprise Document Sharing (XDS) and associated integration profiles. The provision of medical documents in a cross-institutional patient record outside of defined medical pathways requires differentiated authorization management. In this respect, consent documents according to the IHE APPC (Advanced Patient Privacy Consents) profile enable the documentation of the patient's consent, including information about planned authorized people, document types, period and type of document access allowed. Providing access control to medical documentation by the patients themselves is an essential part of the required focusing of medical services on patients. New interoperability standards optimized for use on mobile devices, such as FHIR (Fast Healthcare Interoperability Resources), will enable simplified delivery of patient-centered health records and other medical services on mobile platforms in the future.

Social cognition in an adult epilepsy patient with developmental amnesia

Reports on social cognition in patients with developmental amnesia resulting from bilateral hippocampal lesions are rare, although the link between social cognition and temporal lobe structures is well established. We present the case of a 23-year-old male epilepsy patient, BM, with developmental amnesia due to perinatal cerebral hypoxia. The patient was examined with neuroimaging and neuropsychological methods and compared to IQ-matched patients with epilepsy to control for effects of epilepsy. In addition, we used a test battery that evaluates emotion recognition and theory of mind to study his social cognition abilities. Structural high-resolution magnetic resonance imaging showed bilateral hippocampal atrophy. The comparison to controls showed that, in addition to the well-documented memory disorders in developmental amnesia, BM showed remarkable deficits in 9 out of 17 social cognitive tasks assessing emotion recognition and theory of mind. In contrast, BM's performance on tasks of executive functions was largely preserved. The relevance of deficits in social cognition for patients with developmental amnesia is discussed.

Prediction of hospital visits for the general inpatient care using floating catchment area methods: a reconceptualization of spatial accessibility

Background

The adequate allocation of inpatient care resources requires assumptions about the need for health care and how this need will be met. However, in current practice, these assumptions are often based on outdated methods (e.g. Hill-Burton Formula). This study evaluated floating catchment area (FCA) methods, which have been applied as measures of spatial accessibility, focusing on their ability to predict the need for health care in the inpatient sector in Germany.

Methods

We tested three FCA methods (enhanced (E2SFCA), modified (M2SFCA) and integrated (iFCA)) for their accuracy in predicting hospital visits regarding six medical diagnoses (atrial flutter/fibrillation, heart failure, femoral fracture, gonarthrosis, stroke, and epilepsy) on national level in Germany. We further used the closest provider approach for benchmark purposes. The predicted visits were compared with the actual visits for all six diagnoses using a correlation analysis and a maximum error from the actual visits of ± 5%, ± 10% and ± 15%.

Results

The analysis of 229 million distances between hospitals and population locations revealed a high and significant correlation of predicted with actual visits for all three FCA methods across all six diagnoses up to ρ = 0.79 (p < 0.001). Overall, all FCA methods showed a substantially higher correlation with actual hospital visits compared to the closest provider approach (up to ρ = 0.51; p < 0.001). Allowing a 5% error of the absolute values, the analysis revealed up to 13.4% correctly predicted hospital visits using the FCA methods (15% error: up to 32.5% correctly predicted hospital). Finally, the potential of the FCA methods could be revealed by using the actual hospital visits as the measure of hospital attractiveness, which returned very strong correlations with the actual hospital visits up to ρ = 0.99 (p < 0.001).

Conclusion

We were able to demonstrate the impact of FCA measures regarding the prediction of hospital visits in non-emergency settings, and their superiority over commonly used methods (i.e. closest provider). However, hospital beds were inadequate as the measure of hospital attractiveness resulting in low accuracy of predicted hospital visits. More reliable measures must be integrated within the proposed methods. Still, this study strengthens the possibilities of FCA methods in health care planning beyond their original application in measuring spatial accessibility.

Sarcopenia and myosteatosis in patients undergoing curative radiotherapy for head and neck cancer: Impact on survival, treatment completion, hospital admission and cost

BACKGROUND

Computed tomography (CT) is the gold standard of body composition analysis at the tissue-organ level. The present study aimed to determine the impact of CT-defined sarcopenia and myosteatosis on outcomes, including overall survival, unplanned hospital admissions and related costs, in patients who had completed treatment of curative intent for head and neck cancer (HNC).

METHODS

Retrospective observational study of patients undergoing radiotherapy of curative intent ± other treatment modalities for HNC. Tissue density data derived at the third lumbar vertebra (L3) were evaluated with sarcopenia defined per sex-specific published threshold values for skeletal muscle index, stratified by body mass index and mean skeletal muscle attenuation in HU (Hounsfield units).

RESULTS

Pre- or post-treatment images were available for 79/98 patients (80.6%) and 61/98 patients (62.2%), respectively. Sarcopenia was present in 42/79 patients pre-treatment and 36/61 patients post-treatment, whereas myosteatosis was present in 63/79 patients pre-treatment and 48/61 patients post-treatment. In patients with pre- and post-treatment images (n = 60), the median (range) percentage weight change was -8.5% (-29.9 to +11.7). On multivariable analysis, a post-treatment sarcopenia hazard ratio of 3.87 (95% confidence interval = 1.22-12.24, P = 0.021) and a pre-treatment myosteatosis hazard ratio of 8.86 (95% confidence interval = 1.12-69.88, P = 0.038) were independent predictors of reduced overall survival. There was no difference in radiotherapy or chemotherapy treatment completion based on pre-treatment sarcopenia status. The mean (SD) difference unplanned hospital admission cost was $15 846 ($17 707) for patients without sarcopenia versus $47 945 ($82 688) for patients with sarcopenia at any time point (P = 0.077).

CONCLUSIONS

As CT-defined sarcopenia and myosteatosis hold clinically meaningful prognostic value, muscle status evaluation is recommended in routine clinical practice.

A filtering approach for PET and PG predictions in a proton treatment planning system

Positron emission tomography (PET) and prompt gamma (PG) detection are promising proton therapy monitoring modalities. Fast calculation of the expected distributions is desirable for comparison to measurements and to develop/train algorithms for automatic treatment error detection. A filtering formalism was used for positron-emitter predictions and adapted to allow for its use for the beamline of any proton therapy centre. A novel approach based on a filtering formalism was developed for the prediction of energy-resolved PG distributions for arbitrary tissues. The method estimates PG yields and their energy spectra in the entire treatment field. Both approaches were implemented in a research version of the RayStation treatment planning system. The method was validated against PET monitoring data and Monte Carlo simulations for four patients treated with scanned proton beams. Longitudinal shifts between profiles from analytical and Monte Carlo calculations were within -1.7 and 0.9 mm, with maximum standard deviation of 0.9 mm and 1.1 mm, for positron-emitters and PG shifts, respectively. Normalized mean absolute errors were within 1.2 and 5.3%. When comparing measured and predicted PET data, the same more complex case yielded an average shift of 3 mm, while all other cases were below absolute average shifts of 1.1 mm. Normalized mean absolute errors were below 7.2% for all cases. A novel solution to predict positron-emitter and PG distributions in a treatment planning system is proposed, enabling calculation times of only a few seconds to minutes for entire patient cases, which is suitable for integration in daily clinical routine.

Late Contrast Enhancing Brain Lesions in Proton-Treated Patients With Low-Grade Glioma: Clinical Evidence for Increased Periventricular Sensitivity and Variable RBE

PURPOSE

Late radiation-induced contrast-enhancing brain lesions (CEBLs) on magnetic resonance imaging (MRI) after proton therapy of brain tumors have been observed to occur frequently in regions of high linear energy transfer (LET) and in proximity to the ventricular system. We analyzed 110 patients with low-grade glioma treated with proton therapy to determine whether the risk for CEBLs is increased in proximity to the ventricular system and if there is a relationship between relative biological effectiveness (RBE) and LET.

METHODS AND MATERIALS

We contoured CEBLs identified on follow-up T1-MRI scans and computed dose and dose-averaged LET (LET_d) distributions for all patients using the Monte Carlo method. We then performed cross-validated voxel-level logistic regression to predict local risks for image change and to extract model parameters, such as the RBE. From the voxel-level model, we derived a model for patient-level risk prediction based on the treatment plan.

RESULTS

Of 110 patients, 23 exhibited 1 or several CEBLs on follow-up MRI scans. The voxel-level logistic model has an accuracy as follows: area under the curve of 0.94 and Brier score of 2.6 × 10^-5. Model predictions are a 3-fold increased risk in the 4 mm region around the ventricular system and an LET_d-dependent RBE of, for example, 1.20 for LET_d = 2 keV/μm and 1.50 for LET_d = 5 keV/μm. The patient-level risk model has an accuracy as follows: area under the curve of 0.78 and Brier score of 0.13.

CONCLUSIONS

Our findings present clinical evidence for an increased risk in ventricular proximity and for a proton RBE that increases significantly with increasing LET. We present a voxel-level model that accurately predicts the localization of late MRI contrast change and extrapolate a patient-level model that allows treatment plan-based risk prediction.

Development of selected bacterial groups of the rectal microbiota of healthy calves during the first week postpartum

AIMS

The intestinal microbiota of newborn calves is largely unexplored even if it is of great significance for their future health. Therefore, the aim of the study was to gain a better insight into the development dynamics of certain bacterial groups during the first week of life.

METHODS AND RESULTS

Faecal samples of healthy Simmental calves (dual-purpose breed; n = 80), bottle fed and raised in a dairy farm were taken immediately after birth and at 6/12/24/48/72/168 h (h) after birth. Samples were analysed using cultural, biochemical and molecular-biological methods. The aerobe, anaerobe, Enterobacteriaceae and Enterococcus counts of healthy calves increased significantly between 6 and 24 h postpartum (P <0·05). Apart from the anaerobes, bacterial counts decreased after reaching a plateau at 24-48 h. Enterococcus faecalis was detected in significantly higher counts compared to E. faecium (P <0·05). Lactobacilli developed more slowly and increased until day 7 after birth to a mean value of 6·8 × 107  CFU per g. MALDI-TOF analysis of 2338 lactobacilli isolates resulted in 36 different species.

CONCLUSIONS

Lactobacillus reuteri became the most common Lactobacillus sp. during the first week of life.

SIGNIFICANCE AND IMPACT OF THE STUDY

This fact seems to be very important for the calf's intestinal health because L. reuteri is known to show in vitro bactericidal effects against bacterial pathogens and anti-infective activities against rotaviruses and Cryptosporidium parvum.

WIF1 Suppresses the Generation of Suprabasal Cells in Acanthotic Skin and Growth of Basal Cell Carcinomas upon Forced Overexpression

We analyzed the role of WIF1 in normal and acanthotic epidermis of 12-O-tetradecanoylphorbol-13-acetate (TPA) or all-trans-retinoic acid (ATRA)-treated and basal cell carcinoma (BCC)-bearing mice. WIF1 protein is located in the follicular infundibulum and interfollicular epidermis (IFE) in murine back skin. Within the hyperplastic epidermis of TPA- or ATRA-treated or BCC-bearing murine skin, WIF1 and Keratin 10 overlap in Ki67^⁻ suprabasal layers, while basal epidermal layers expressing Ki67, and BCCs expressing Wif1 mRNA, are free of WIF1 protein. This is similar in human skin, with the exception that WIF1 protein is found in single Ki67^⁻ basal epidermal cells in normal skin and additionally in Ki67⁺ cells in acanthotic skin. Wif1-deficiency enhances acanthosis of the murine BCC-associated epidermis, which is accompanied by an increase of Ki67⁺ and of Sca-1⁺ basal cells. WIF1 overexpression in allografted BCC-derived keratinocytes prevents growth and keratinization, involving enhanced phosphorylation of protein kinase C and extracellular signal-regulated kinase 1 and arguably factors secreted by the in vivo environment. In summary, WIF1 protein marks suprabasal layers in the normal IFE. It is also present in the epidermis overlaying BCCs where it diminishes proliferation of basal cells and production of differentiating suprabasal cells. In addition, WIF1 can prevent proliferation and keratinization of BCC-related keratinocytes.

Regulation and Role of GLI1 in Cutaneous Squamous Cell Carcinoma Pathogenesis

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin tumor in humans. Although current therapies are sufficient to clear the tumor in many cases, the overall risk of cSCC metastasis is still 5%. Alternative treatment options could help to overcome this situation. Here we focused on the role of the Hedgehog (HH) signaling pathway and its interplay with epidermal growth factor receptor (EGFR) signaling in cSCC. The analyses revealed that, despite lack of Sonic HH (SHH) expression, a subset of human cSCC can express GLI1, a marker for active HH signaling, within distinct tumor areas. In contrast, all tumors strongly express EGFR and the hair follicle stem cell marker SOX9 at the highly proliferative tumor-stroma interface, whereas central tumor regions with a more differentiated stratum spinosum cell type lack both EGFR and SOX9 expression. In vitro experiments indicate that activation of EGFR signaling in the human cSCC cell lines SCL-1, MET-1, and MET-4 leads to GLI1 inhibition via the MEK/ERK axis without affecting cellular proliferation. Of note, EGFR activation also inhibits cellular migration of SCL-1 and MET-4 cells. Because proliferation and migration of the cells is also not altered by a GLI1 knockdown, GLI1 is apparently not involved in processes of aggressiveness in established cSCC tumors. In contrast, our data rather suggest a negative correlation between Gli1 expression level and cSCC formation because skin of Ptch^+/- mice with slightly elevated Gli1 expression levels is significantly less susceptible to chemically-induced cSCC formation compared to murine wildtype skin. Although not yet formally validated, these data open the possibility that GLI1 (and thus HH signaling) may antagonize cSCC initiation and is not involved in cSCC aggressiveness, at least in a subset of cSCC.

Offline imaging of positron emitters induced by therapeutic helium, carbon and oxygen ion beams with a full-ring PET/CT scanner: experiments in reference targets

In vivo verification of light ion therapy based on positron-emission tomography (PET) imaging of irradiation induced patient activation relies on activity predictions from Monte-Carlo (MC) or analytical computational engines for comparison to the measurements. In order to achieve the necessary accuracy, experimental data are indispensable for the validation of the calculation models. For this we irradiated thick reference targets with mono-energetic helium, carbon and oxygen ion beams and measured the resulting material activation offline with a commercial full-ring PET/CT scanner located nearby the treatment room. Acquired PET data were analysed over time to separate the activity contribution of different radionuclides. Determined production yields were compared to published findings obtained from in-beam activation measurements with a limited-angle double-head PET camera. In addition, we investigated the time-dependence of the measured radionuclide-specific contributions and of the distal activity range, as well as the lateral spread of the activity signal as a function of beam penetration depth. We present radionuclide-specific depth-resolved activity distributions and production yields for the radionuclides [Formula: see text], [Formula: see text] and [Formula: see text], dominating irradiation-induced patient activation. We observe systematically lower production yields with a ratio between the dual-head and our full-ring PET measurements of, on average, 1.7 and 1.3 for the oxygen and carbon beam irradiations, and 1.7 (2.1) for the high (low) energy helium beam irradiations. Findings on the temporal development of the activity range confirm the expectation, with the oxygen beam induced signal being the most sensitive scenario. The experimental data reported in this work, acquired with a state-of-the-art full ring PET scanner, provide a comprehensive and consistent basis for the benchmarking of PET signal calculation engines. In particular, they can support a fine-tuning of the underlying physics models used by the respective implementation and therefore improve the accuracy of PET-based therapy verifications at current and future treatment facilities.

Biophysical modeling and experimental validation of relative biological effectiveness (RBE) for 4He ion beam therapy

BACKGROUND

Helium (4He) ion beam therapy provides favorable biophysical characteristics compared to currently administered particle therapies, i.e., reduced lateral scattering and enhanced biological damage to deep-seated tumors like heavier ions, while simultaneously lessened particle fragmentation in distal healthy tissues as observed with lighter protons. Despite these biophysical advantages, raster-scanning 4He ion therapy remains poorly explored e.g., clinical translational is hampered by the lack of reliable and robust estimation of physical and radiobiological uncertainties. Therefore, prior to the upcoming 4He ion therapy program at the Heidelberg Ion-beam Therapy Center (HIT), we aimed to characterize the biophysical phenomena of 4He ion beams and various aspects of the associated models for clinical integration.

METHODS

Characterization of biological effect for 4He ion beams was performed in both homogenous and patient-like treatment scenarios using innovative models for estimation of relative biological effectiveness (RBE) in silico and their experimental validation using clonogenic cell survival as the gold-standard surrogate. Towards translation of RBE models in patients, the first GPU-based treatment planning system (non-commercial) for raster-scanning 4He ion beams was devised in-house (FRoG).

RESULTS

Our data indicate clinically relevant uncertainty of ±5-10% across different model simulations, highlighting their distinct biological and computational methodologies. The in vitro surrogate for highly radio-resistant tissues presented large RBE variability and uncertainty within the clinical dose range.

CONCLUSIONS

Existing phenomenological and mechanistic/biophysical models were successfully integrated and validated in both Monte Carlo and GPU-accelerated analytical platforms against in vitro experiments, and tested using pristine peaks and clinical fields in highly radio-resistant tissues where models exhibit the greatest RBE uncertainty. Together, these efforts mark an important step towards clinical translation of raster-scanning 4He ion beam therapy to the clinic.

Risk of institutionalization following fragility fractures in older people

Previously independent living older people suffering fractures of the hip have a high risk of new admission to a nursing home during the subsequent months. This study shows that older people admitted to hospital for fractures of the pelvis and spine have a similar risk of admission to a nursing home.

INTRODUCTION

Fall-related fractures are a serious threat to the health and well-being of older persons. Long-term consequences of hip fractures such as institutionalization and mortality are well-known. The impact of other fragility fractures is less well-understood. The aim of this study was to estimate risks of institutionalization and death for different fragility fractures and compare them with the corresponding risks after hip fracture.

METHODS

Data was retrieved from a German health insurance company. Between 2005 and 2008 more than 56,000 community-dwelling people with a hospital admission or discharge diagnosis of a fracture of the femur, spine, pelvis, proximal humerus, distal radius, tibia, or fibula were included. Crude and age-adjusted 6-month incidence rates for institutionalization and death were calculated. To compare the risks of institutionalization or mortality of non-hip fractures with the risk after hip fracture, multivariate regression models were applied.

RESULTS

Crude institutionalization rates and mortality were highest in patients with hip fracture. However, after adjustment for age, functional status, and comorbidity, risks of institutionalization after fractures of pelvis (relative risk (RR), 0.94; 95% confidence interval (CI) 0.86; 1.02 in women and 0.89; 95% CI 0.70; 1.12 in men), and spine (RR, 0.95; 95% CI 0.87; 1.03 in women and 0.91; 95% CI 0.76; 1.08 in men) were not statistically different compared to the risk after hip fracture.

CONCLUSIONS

The risk of institutionalization after fractures of the spine and pelvis was similar to the risk after hip fracture. These fracture sites seem to be associated with a significant decline in physical function.