Osseointegration of photodynamic active biomaterials for bone regeneration in an animal bone model over a period of 12 months

OBJECTIVES

Previous efforts led to the development of two different polymeric biomaterials for periodontal regeneration with antibacterial photodynamic surface activity. The present study aimed to investigate osseointegration and bone formation of both materials in an ovine model.

METHODS

Both biomaterials: 1) urethane dimethacrylate-based Biomaterial 1 (BioM1) and 2) tri-armed oligoester-urethane methacrylate-based Biomaterial 2 (BioM2) are enriched with beta-tri-calcium phosphate and the photosensitizer meso-tetra(hydroxyphenyl)chlorin (mTHPC). These materials were implanted in non-critical size bone defects in the sheep femur (n = 16) and tibia (n = 8). Empty defects served as controls (n = 16). Polyfluorochrome sequential bone labeling was carried out at baseline and after 3, 6, and 12 months. Animals were sacrificed after 12 months. Bone specimens (n = 40) were fixed and subjected to microtomographic analysis (µCT) for the evaluation of the bone-volume-fraction (BV/TV), trabecular number and trabecular thickness. Subsequently, histological sections were arranged and polyfluorochrome sequential bone labeling was analyzed by confocal laser scanning microscopy (cLSM).

RESULTS

cLSM analysis revealed that highest remodeling and bone formation activity occurred during the second half of the study period (6-12 months). Bone formation in the tibia was significantly lower for the control (2.71 ± 1.26%) as compared to BioM1 (6.01 ± 2.99%) and BioM2 (6.45 ± 2.12%); (p = 0.006, p = 0004). Micro-computed tomography revealed a BV/TV volume fraction of 44.72 ± 9.01% in femur defects filled with BioM1 which was significantly higher compared to the control (32.27 ± 7.02%; p = 0.01). Bone architecture (trabecular number, trabecular thickness) did not significantly differ from the self-healed defects.

SIGNIFICANCE

Both biomaterials, especially BioM1 showed good osseointegration and bone formation characteristics and can be recommended for further examination in periodontal regeneration studies.

Peanut-induced anaphylaxis in children and adolescents: Data from the European Anaphylaxis Registry

BACKGROUND

Peanut allergy has a rising prevalence in high-income countries, affecting 0.5%-1.4% of children. This study aimed to better understand peanut anaphylaxis in comparison to anaphylaxis to other food triggers in European children and adolescents.

METHODS

Data was sourced from the European Anaphylaxis Registry via an online questionnaire, after in-depth review of food-induced anaphylaxis cases in a tertiary paediatric allergy centre.

RESULTS

3514 cases of food anaphylaxis were reported between July 2007 - March 2018, 56% in patients younger than 18 years. Peanut anaphylaxis was recorded in 459 children and adolescents (85% of all peanut anaphylaxis cases). Previous reactions (42% vs. 38%; p = .001), asthma comorbidity (47% vs. 35%; p < .001), relevant cofactors (29% vs. 22%; p = .004) and biphasic reactions (10% vs. 4%; p = .001) were more commonly reported in peanut anaphylaxis. Most cases were labelled as severe anaphylaxis (Ring&Messmer grade III 65% vs. 56% and grade IV 1.1% vs. 0.9%; p = .001). Self-administration of intramuscular adrenaline was low (17% vs. 15%), professional adrenaline administration was higher in non-peanut food anaphylaxis (34% vs. 26%; p = .003). Hospitalization was higher for peanut anaphylaxis (67% vs. 54%; p = .004).

CONCLUSIONS

The European Anaphylaxis Registry data confirmed peanut as one of the major causes of severe, potentially life-threatening allergic reactions in European children, with some characteristic features e.g., presence of asthma comorbidity and increased rate of biphasic reactions. Usage of intramuscular adrenaline as first-line treatment is low and needs to be improved. The Registry, designed as the largest database on anaphylaxis, allows continuous assessment of this condition.

Schimmel im Outdoor-Bereich – klinisch bedeutsam?

Alternaria alternata ist ein bedeutsames Inhalationsallergen. Bei ca. 6 % der in unserer Einrichtung betreuten Patienten mit einer Beschwerdesymptomatik an den oberen und unteren Atemwegen in den Sommermonaten fanden wir eine Sensibilisierung gegenüber diesem Allergen. Sehr häufig sind bei Kindern und Jugendlichen die Sporen für die Entwicklung oder Persistenz einer unspezifischen bronchialen Hyperreaktivität und zum Teil für therapierefraktären Reizhusten bzw. therapierefraktäres Asthma im Sommer verantwortlich. Wenn bei Graspollenallergikern die Beschwerden über Ende Juni hinaus persistieren, kann eine Allergie gegenüber Beifußpollen, aber auch eine Allergie gegenüber Alternariasporen ursächlich sein. Häufig bestehen Graspollen- und Alternariaallergie gleichzeitig. In den Sommermonaten treten des Öfteren gleichzeitig hohe Sporen- und hohe Pollenkonzentrationen auf. Um zu differenzieren, welches Allergen z. B. für schwerere allergische Reaktionen, vor allen Dingen für asthmatische Beschwerden verantwortlich ist, weisen wir auf die Notwendigkeit des Führens eines Symptomkalenders durch die Patienten hin. Insbesondere bei Doppel- oder Dreifach-Sensibilisierungen werden Therapieentscheidungen und -empfehlungen erleichtert. Informationen zu regionalen Pollen- und Alternariasporenbelastungen sollten zur Verfügung stehen (Stiftung Deutscher Polleninformationsdienst, Deutscher Wetterdienst). Wie hoch auch in Deutschland die Alternariasporenbelastung sein kann, zeigen die Auswertungen der regionalen Pollenfalle Treuenbrietzen. Bedeutsam sind Sporenfragmente von Alternaria alternata. Diese treten z. B. nach Gewittern auf und haben für die Auslösung von Asthmaexazerbationen eine hohe Relevanz. Vor dem Beginn einer SIT mit Alternaria alternata sollte die klinische Bedeutsamkeit der Sensibilisierung durch Schleimhautprovokationstests bewiesen werden.

Die Indikationsstellung für die Durchführung einer spezifischen Immuntherapie mit Alternaria alternata entspricht dem Vorgehen auch bei anderen Inhalationsallergien, insbesondere Pollenallergien. Entsprechende Empfehlungen sind in der aktuellen Leitlinie nachzulesen 1. Die Allergenextrakte von Alternaria alternata sind in der Anwendung und Verträglichkeit ebenso sicher wie die anderer Inhalationsallergene.

Antimicrobial photodynamic active biomaterials for periodontal regeneration

OBJECTIVE

Biomaterials for periodontal regeneration may have insufficient mechanical and antimicrobial properties or are difficult to apply under clinical conditions. The aim of the present study was to develop a polymeric bone grafting material of suitable physical appearance and antimicrobial photodynamic activity.

METHODS

Two light curable biomaterials based on urethane dimethacrylate (BioM1) and a tri-armed oligoester-urethane methacrylate (BioM2) that additionally contained a mixture of β-tricalcium phosphate microparticles and 20wt% photosensitizer mTHPC (PS) were fabricated and analyzed by their compressive strength, flexural strength and modulus of elasticity. Cytotoxicity was observed by incubating eluates and in direct-contact to MC3T3-E1 cells. Antimicrobial activity was ascertained on Porphyromonas gingivalis and Enterococcus faecalis upon illumination with laser light (652nm, 1×100J/cm², 2×100J/cm²).

RESULTS

The compressive strength, flexural strength and elastic modulus were, respectively, 311.73MPa, 22.81MPa and 318.85MPa for BioM1+PS and 742.37MPa, 7.58MPa and 406.23MPa for BioM2+PS. Both materials did not show any cytotoxic behavior. Single laser-illumination (652nm) caused total suppression of P. gingivalis (BioM2+PS), while repeated irradiation reduced E. faecalis by 3.7 (BioM1+PS) and 3.1 (BioM2+PS) log-counts.

SIGNIFICANCE

Both materials show excellent mechanical and cytocompatible properties. In addition, irradiation with 652nm induced significant bacterial suppression. The manufactured biomaterials might enable a more efficient cure of periodontal bone lesions. Due to the mechanical properties functional stability might be increased. Further, the materials are antimicrobial upon illumination with light that enables a trans-mucosal eradication of residual pathogens.

How to diagnose mould allergy? Comparison of skin prick tests with specific IgE results

BACKGROUND

Diagnosis of mould allergy is complicated due to the heterogeneity of the test material and the decrease in the number of commercial mould skin test solutions that are currently available.

OBJECTIVES

The aim of this study was to compare skin prick tests (SPT) from different manufacturers to one another and concurrently with sIgE tests for Aspergillus fumigatus (Asp f), Cladosporium herbarum (Cla h), Penicillium chrysogenum (Pen ch), Alternaria alternata (Alt a) and Aspergillus versicolor (Asp v) to ascertain a feasible diagnostic procedure for mould sensitization.

METHODS

In this multi-centre study, 168 patients with mould exposure and/or mould-induced respiratory symptoms were included. Mould SPT solutions were analysed biochemically and tested in duplicate on patients' arms. Specific IgE (sIgE) concentrations to corresponding mould species and mould mix (mx1) were measured by ImmunoCAP. SPTs in accordance with one another and with sIgE were further considered. The test efficiency was calculated using receiver-operating characteristic (ROC) analysis.

RESULTS

Mould sensitization was more frequently detected by the SPT (90 of 168) than by the sIgE tests (56 of 168). Concordances of double SPT positives were only sufficient (≥ 80%) for environmental allergens, two Asp f and three Alt a SPT solutions, whereas all other mould solutions revealed concordances < 80%. The antigen content of SPT solutions was positively associated with concordant SPT double values as well as with sIgE. Taking sIgE as the 'positive standard', all mould SPT solutions revealed test efficiencies > 80%, but varied up to 20% in sensitivity and positive predictive value with the exception of Alt a.

CONCLUSIONS

SPT solutions are sensitive and essential diagnostic tools for the detection of mould sensitization. Our recommendation for diagnosis would be to test at least Alt a, Asp f and Pen ch using SPT and additional sIgE test to mx1.

Long-term clinical effects of aspirin-desensitization therapy among patients with poorly controlled asthma and non-steroidal anti-inflammatory drug hypersensitivity: An exploratory study

BACKGROUND

According to the Global Initiative for Asthma (GINA), the levels of asthma symptom control can be divided into controlled, partially controlled and uncontrolled asthma. Optional therapy for non-steroidal anti-inflammatory drugs (NSAIDs)-hypersensitive asthmatics uses aspirin desensitization, but until now, this therapy is not established in difficult to treat cases. The aim of this study was to evaluate the efficacy of aspirin desensitization in patients with poorly controlled asthma.

METHODS

Patients with poorly controlled asthma, NDAIDs hypersensitivity and aspirin desensitization were included in the retrospective study. The data were compared to those obtained from patients with controlled asthma and aspirin therapy. Lung function, levels of asthma symptom control, asthma medication, the size of nasal polyps (NP) and smell function were evaluated over 18 months.

RESULTS

Thirty-two patients were included in the study (uncontrolled/partially controlled asthma n=12; controlled asthma n=20). After 18 months of follow-up, the patients with poorly controlled asthma had significantly increased forced expiratory volume in 1s (FEV1) values, as compared to the baseline (66-82%; p=0.02), the levels of asthma control improved significantly (p<0.01). The asthma medication was reduced. In the group of controlled asthma the FEV1 values did not increase significantly (91.9-92.4%; p>0.05) and the asthma medication was constant. In relation to nasal parameters the sense of smell improved significantly in both groups, NP-scores did not differ significantly.

CONCLUSIONS

Patients with a poorly controlled asthma and NSAIDs hypersensitivity profit from an add-on aspirin therapy.

Käfigverbindungen im System P4S3-As4S3 / Cage Compounds in the System P4S3-AS4S3

Mixtures of P4S3 and As4S3 were investigated. The system reveals a broad metastable region of solid solubility. At the composition PAs3S3 new structures are obtainable after various thermal treatments. In the mixtures six different cage molecules (P4-xAsxS3 (x=1−3)) were found. PAs3S3 is the most stable of the mixed cages. At higher temperature a plastic-crystalline modification, at the composition PAs3S3 two further high temperature modifications are observed. NMR and mass spectra, and d-values of the modifications are reported, and the high temperature behaviour of all mixed cages is described.

Quantitative Evaluation of Elastic Properties of Nano-Crystalline Nickel Using Atomic Force Acoustic Microscopy

Atomic force acoustic microscopy (AFAM) is a near-field technique, where the vibration behavior of a micro-fabricated elastic cantilever beam in contact with a sample surface is sensitive to its local elastic properties. The resolution of this technique is given by the contact radius a c of the atomic force microscope sensor-tip on the sample surface. Taking into account only the Hertzian forces, a c depends on the static load applied by the cantilever, on the elastic constants of the tip and the sample and on the geometry of the contacting bodies. The shape of the sensor tip used in atomic force acoustic microscopy is between a sphere and a flat punch. Hence a c extends from just below 10nm to a few tens of nanometers. In this review, we give an overview of the AFAM technique, present data on the indentation moduli of nanocrystalline nickel, and discuss some of the error sources in quantitative AFAM. The AFAM indentation moduli measured are comparable to the values obtained by nanoindentation and lower than the indentation moduli calculated from ultrasonic velocity measurements. There seems to be a decrease of the indentation modulus with decreasing grain size for grain sizes below 30nm. The data are discussed taking into account X-ray diffraction and electron back-scattering data revealing some texture and macro-strain due to internal stresses in the samples investigated.

Evaluation of the contact resonance frequencies in atomic force microscopy as a method for surface characterisation (invited)

The combination of ultrasound with atomic force microscopy (AFM) opens the high lateral resolution of scanning probe techniques in the nanometer range to ultrasonics. One possible method is to observe the resonance frequencies of the AFM sensors under different tip-sample interaction conditions. AFM sensors can be regarded as small flexible beams. Their lowest flexural and torsional resonance frequencies are usually found to be in a range between several kHz and several MHz depending on their exact geometrical shape. When the sensor tip is in a repulsive elastic contact with a sample surface, the local indentation modulus can be determined by the contact resonance technique. Contact resonances in the ultrasonic frequency range can also be used to improve the image contrast in other dynamic techniques as, for example, in the so-called piezo-mode. Here, an alternating electric field is applied between a conducting cantilever and a piezoelectric sample. Via the inverse piezoelectric effect, the sample surface is set into vibration. This excitation is localised around the contact area formed by the sensor tip and the sample surface. We show applications of the contact resonance technique to piezoelectric ceramics.

Flow cytometric analysis of mitogen-induced activation of rainbow trout (Oncorhynchus mykiss) peripheral blood leucocytes

Proliferation of rainbow trout peripheral blood leucocytes in vitro is usually assessed by measuring incorporated tritiated thymidine. In this report we monitored the in vitro proliferative response to the mitogen Concanavalin A (Con A) by means of flow cytometry (FCM) and 3H-thymidine incorporation. When analysed by FCM, blood leucocytes displayed two main cell populations with distinct forward and side scatter (FSC/SSC) characteristics: lymphocytes with low FSC/SSC values and non-lymphoid leucocytes (NLL) with increased FSC/SSC values. The nature of these cell types were confirmed by microscopy. Interestingly, the FSC/SSC pattern of lymphocytes remained unchanged after in vitro stimulation with Con A, whereas cells from the NLL population showed a marked shift towards increased FSC values. In stimulated cultures, the increase of FSC values of the NLL population significantly correlated with contemporarily measured 3H-thymidine incorporation (r = 0.7, P < 0.001). The mitogenic response of blood leucocytes originating from different individual fish varied over wide ranges. It was found to be related to the numbers of NLL present in the leucocyte sample. The present results show that qualitative and quantitative FCM analysis of morphological parameters (FSC/SSC) of blood leucocytes makes it possible to discriminate between leucocyte populations of the rainbow trout and to monitor cell proliferation experiments.

Quantitative determination of contact stiffness using atomic force acoustic microscopy

Atomic force acoustic microscopy is a near-field technique which combines the ability of ultrasonics to image elastic properties with the high lateral resolution of scanning probe microscopes. We present a technique to measure the contact stiffness and the Young's modulus of sample surfaces quantitatively, with a resolution of approximately 20 nm, exploiting the contact resonance frequencies of standard cantilevers used in atomic force microscopy. The Young's modulus of nanocrystalline ferrite films has been measured as a function of oxidation temperature. Furthermore, images showing the domain structure of piezoelectric lead zirconate titanate ceramics have been taken.

Evaluation of alpha-tocopherol antioxidant activity in microsomal lipid peroxidation as detected by low-level chemiluminescence

The significance of microsomal vitamin E in protecting against the free-radical process of lipid peroxidation was evaluated with the low-level-chemiluminescence technique in microsomal fractions from vitamin E-deficient and control rats. The induction period that normally precedes the ascorbate/ADP/Fe3+-induced lipid peroxidation was taken as reflecting the microsomal vitamin E content and was found to be 5-6-fold decreased in microsomal fractions from vitamin E-deficient rats. Supplementation of microsomal fractions from vitamin E-deficient rats with exogenous vitamin E partially restores the induction period observed in that from control rats. The decrease in chemiluminescence intensity and the increase in the induction period both correlate linearly with the amount of vitamin E added. However, the efficiency of exogenous vitamin E is about 50-fold lower than that exerted by the naturally occurring vitamin E in microsomal membranes. These observations are discussed in terms of the process of re-incorporation of vitamin E into membranes, the experimental model for lipid peroxidation selected, and the method to evaluate lipid peroxidation, namely low-level chemiluminescence.

Peroxisomal fatty acid oxidation as detected by H2O2 production in intact perfused rat liver

1. H2O2 formation associated with the metabolism of added fatty acids was quantitatively determined in isolated haemoglobin-free perfused rat liver (non-recirculating system) by two different methods. 2. Organ spectrophotometry of catalase Compound I [Sies & Chance (1970) FEBS Lett. 11, 172-176] was used to detect H2O2 formation (a) by steady-state titration with added hydrogen donor, methanol or (b) by comparison of fatty-acid responses with those of the calibration compound, urate. 3. In the use of the peroxidatic reaction of catalase, [14C]methanol was added as hydrogen donor at an optimal concentration of 1 mM in the presence of 0.2 mM-L-methionine, and 14CO2 production rates were determined. 4. Results obtained by the different methods were similar. 5. The yield of H2O2 formation, expressed as the rate of H2O2 formation in relation to the rate of fatty-acid supply, was less than 1.0 in all cases, indicating that, regardless of chain length, less than one acetyl unit was formed per mol of added fatty acid by the peroxisomal system. In particular, the standard substrate used with isolated peroxisomal preparations (C16:0 fatty acid) gave low yield (close to zero). Long-chain monounsaturated fatty acids exhibit a relatively high yield of H2O2 formation. 6. The hypolipidaemic agent bezafibrate led to slightly increased yields for most of the acids tested, but the yield with oleate was decreased to one-half the original yield. 7. It is concluded that in the intact isolated perfused rat liver the assayable capacity for peroxisomal beta-oxidation is used to only a minor degree. However, the observed rates of H2O2 production with fatty acids can account for a considerable share of the endogenous H2O2 production found in the intact animal.