Interplay of structure and photophysics of individualized rod-shaped graphene quantum dots with up to 132 sp² carbon atoms

Nanographene materials are promising building blocks for the growing field of low-dimensional materials for optics, electronics and biophotonics applications. In particular, bottom-up synthesized 0D graphene quantum dots show great potential as single quantum emitters. To fully exploit their exciting properties, the graphene quantum dots must be of high purity; the key parameter for efficient purification being the solubility of the starting materials. Here, we report the synthesis of a family of highly soluble and easily processable rod-shaped graphene quantum dots with fluorescence quantum yields up to 94%. This is uncommon for a red emission. The high solubility is directly related to the design of the structure, allowing for an accurate description of the photophysical properties of the graphene quantum dots both in solution and at the single molecule level. These photophysical properties were fully predicted by quantum-chemical calculations.

Physical activity counseling during and following stem cell transplantation - patients' versus advisors' perspectives

BACKGROUND

People receiving hematopoietic stem cell transplantation (HSCT) endure long phases of therapy and immobility, which diminish their physical activity (PA) level leading to physical deconditioning. One of the reasons is a lack of clarity on the part of those who work in oncology clinical settings of their role in assessing, advising, and referring patients to exercise. Therefore, our study investigates reported physical activity counseling behavior of health care professionals (HCPs) and the patient perspective on this topic.

METHODS

Physicians (N = 52), nurses (N = 52) physical therapists (N = 26), and patients receiving HSCT (N = 62) participated in a nationwide cross-sectional online-survey. Patients' preferred source of information concerning PA was determined. We examined HCPs self-assessed PA counseling behavior and patients' PA recall by assessing the use of the 5As (Ask, Advice, Agree, Assist, Arrange). Analysis of survey responses was descriptive. Univariate multinomial logistic regression examined whether sociodemographic factors and patient characteristics influence the response behavior.

RESULTS

Physicians and PA specialists were patients' preferred source of information regarding PA. A large discrepancy between HCPs' perception and the degree to which HSCT patients recall advice became apparent; profound counseling steps like making referrals were less often recalled in our patient sample. Inactive patients reported to receive less basic PA counseling by physicians.

CONCLUSION

Future research should identify the requirements to increase patients' recall concerning PA counseling in the setting of HSCT. Important messages about PA need to be made more salient to those who are less active and less engaged.

Quantification of mechanical properties in long-term in vivo used silicone catheter lines according to DIN 10555-3

BACKGROUND

Totally implantable central venous access port devices are crucial for intravenous application of chemotherapeutics and long-term therapy for chronic disease. Common complications include thrombosis and device fracture related to altered material properties through exposure in situ. This study exhibits whether uniaxial tensile properties (DIN 10555-3) of in vivo used catheters prove inferior to unused catheters.

MATERIAL AND METHODS

5 unused, originally packed silicone catheters were cut into 6 segments of 50 mm: 3 segments each were cleaned via cleaning solution (n = 15) while 3 segments were left unattended (n = 15). Distal segments (50 mm) of long-term in vivo used silicone catheters were cleaned before testing (n = 33). Overall mechanical behavior was tested in a custom-made self-centering, torsion free carrier. Maximum force stress at failure, strain at failure and Young's modulus were determined and statistically analyzed.

FINDINGS

Unused catheters showed no significant difference in testing. in vivo used catheters exhibited 20% lower maximal force than unused catheters (p < 0.001), strain at break (p 〈0,001), and 7% higher elastic modulus (p = 0.004; power: 0.845). Due to a constant cross section area, stress at failure was proportional to maximum force (p < 0.001). Relation between determined parameters and dwell times was non-significant.

INTERPRETATION

In vivo long-term used silicone catheters showed significantly lower ultimate strength than unused ones. It is likely that in situ altering changes the mechanical properties of catheters and may potentially lead to failure.

Acromioclavicular joint suture button repair leads to coracoclavicular tunnel widening

PURPOSE

Biomechanical evaluation of three different suture button devices used in acromioclavicular joint repair and analysis of their effect on post-testing tunnel widening.

METHODS

Eighteen human shoulder girdles were assigned into three groups with a similar mean bone mineral density. Three different single-tunnel acromioclavicular repair devices were tested: (1) AC TightRope^® with FiberWire; (2) AC Dog Bone^™ Button with FiberTape; (3) Low Profile AC Repair System. Biomechanical testing was performed simulating the complex movement of the distal clavicle as follows. A vertical load of 80 N was applied continuously. The rotation of the clavicle about its long axis was set at 10° anterior and 30° posterior for 2500 cycles at 0.25 Hz. The horizontal translation of the clavicle was set at 6 mm medial and 6 mm lateral for 10,000 cycles at 1 Hz. The coracoclavicular distance was measured before and after testing. After testing, each sample underwent micro-CT analysis. Following 3D reconstruction, the area of the bone tunnels was measured at five defined cross sections.

RESULTS

In TightRope^® and Dog Bone^™ groups, all samples completed testing, whereas in the Low Profile group, three out of six samples showed system failure. The mean absolute difference of coracoclavicular distance after testing was significantly greater in the Low Profile group compared to TightRope^® and Dog Bone^™ groups (4.3 ± 1.3 mm vs 1.9 ± 0.7 mm vs 1.9 ± 0.8 mm; p = 0.001). Micro-CT analysis of the specimens demonstrated significant tunnel widening in the inferior clavicular and superior coracoid regions in all three groups (p < 0.05).

CONCLUSION

Significant tunnel widening can be observed for all devices and is primarily found in the inferior parts of the clavicle and superior parts of the coracoid. The Low Profile AC Repair System showed inferior biomechanical properties compared to the AC TightRope^® and AC Dog Bone^™ devices. Therefore, clinicians should carefully select the type of acromioclavicular repair device used and need to consider tunnel widening as a complication.

Sentinel lymph node biopsy for early stage tongue cancer-a 14-year single-centre experience

This study was performed to report the usage of sentinel lymph node biopsy (SLNB) in clinical stage I or II tongue cancer patients with cN0 necks seen over a 14-year period. Data were collected prospectively, and a retrospective analysis was performed of 41 patients with early stage oral squamous cell carcinoma of the tongue and a cN0 neck. Sentinel lymph node (SLN)-positive patients underwent elective neck dissection, whereas SLN-negative patients were kept under careful observation. Seven of the 41 (17%) patients enrolled in the study were found to have occult metastases. The patients were followed up for a mean duration of 92 months (range 60-144 months). The neck recurrence rate for SLN-positive patients was 0% and for SLN-negative patients was 3%. The authors recommend the routine use of SLNB in patients with early stage oral squamous cell carcinoma of the tongue and a cN0 neck. Furthermore, special focus should be placed on isolated tumour cells, as their presence is of high clinical relevance.

Unsaturated cryptophanes: Toward dual PHIP/hyperpolarised xenon sensors

Cryptophanes, cage-molecules constituted of aromatic bowls, are now well recognised as powerful xenon hosts in ¹²⁹ Xe NMR-based biosensing. In the quest of a dual probe that can be addressed only by NMR, we have studied three cryptophanes bearing a tether with an unsaturated bond. The idea behind this is to build probes that can be detected both via hyperpolarised ¹²⁹ Xe NMR and para-hydrogen induced polarisation ¹ H NMR. Only two of the three cryptophanes experience a sufficiently fast hydrogenation enabling the para-hydrogen induced polarisation effect. Although the in-out xenon exchange properties are maintained after hydrogenation, the chemical shift of xenon encaged in these two cryptophanes is not strikingly modified, which impedes safe discrimination of the native and hydrogenated states via ¹²⁹ Xe NMR. However, a thorough examination of the hyperpolarised ¹ H spectra reveals some interesting features for the catalytic process and gives us clues for the design of doubly smart ¹ H/¹²⁹ Xe NMR-based biosensors.

RPYFMM: Parallel Adaptive Fast Multipole Method for Rotne-Prager-Yamakawa Tensor in Biomolecular Hydrodynamics Simulations

RPYFMM is a software package for the efficient evaluation of the potential field governed by the Rotne-Prager-Yamakawa (RPY) tensor interactions in biomolecular hydrodynamics simulations. In our algorithm, the RPY tensor is decomposed as a linear combination of four Laplace interactions, each of which is evaluated using the adaptive fast multipole method (FMM) [1] where the exponential expansions are applied to diagonalize the multipole-to-local translation operators. RPYFMM offers a unified execution on both shared and distributed memory computers by leveraging the DASHMM library [2, 3]. Preliminary numerical results show that the interactions for a molecular system of 15 million particles (beads) can be computed within one second on a Cray XC30 cluster using 12, 288 cores, while achieving approximately 54% strong-scaling efficiency.

Test method for mechanical properties of implantable catheters according to DIN 10555-3

To enable causal analysis of port catheter failure, this study aimed to develop an experimental setup for uniaxial tensile tests that addresses the specific requirements of highly elastic medical catheters; and to quantify parameters of the catheters' mechanical competence with respect to effects of artificial aging. Segments of 6F-polyurethane catheters were tested in their native status, after chemical and after mechanical aging. Tension experiments were performed with a rate of 220 mm/min until catheter failure. Material behavior was analyzed based on load cell measurements of the universal test system and an additional optical distance registration. The Young's modulus, the ultimate stress and the ultimate strain were determined. Chemical aging significantly decreased Young's modulus (84%; p = 0.001) and ultimate stress (83%; p < 0.001), whereas mechanical aged samples demonstrated similar results for the Young's modulus (p = 0.772) and a non-significant rise of ultimate stress (13%; p = 0.128). Ultimate strain did not differ significantly regardless of the pretreatment. The results proof reliability, reproducibility and sensitivity to quantify artificial aging induced variations and also promise to detect deviations in material features caused by long-term clinical usage of catheters.

New horizons for the in vivo assessment of major aspects of bone quality

The Biomechanically founded individualised osteoporosis Assessment and treatment (BioAsset) consortium pursues experimental and clinical studies in the context of skeletal effects of bisphosphonate treatment. Here, first results using newly developed diagnostic methods in a set of vertebral bone specimen obtained from donors with documented bisphosphonate history ranging from 0 to more than 5 years of treatment are presented. A new thoracolumbar quantitative computed tomography (QCT) protocol covering T6 to L4 plus high-resolution QCT (HRQCT) assessment of T12 were compared with high-resolution peripheral QCT (HRpQCT) and micro-CT scans of excised specimens serving as gold standard techniques. Finite element (FE) modelling was performed. Material, ultrastructural, and micromechanical properties were tested on a set of single trabeculae obtained from the donor specimens. A newly developed quantitative ultrasound (QUS) device for measuring the anisotropy of cortical material properties at the tibia was designed and built. The thoracolumbar QCT protocol permitted in situ imaging with good image quality and automated segmentation of vertebral bodies in the whole range from T6 to L4. The duration of bisphosphonate treatment was significantly associated with increased levels of mineralization and this effect could be measured with HRQCT performed on excised specimens. Microstructural parameters contributed to vertebral bone strength modelled by FE analysis independently of bone mineral density. The new QUS tibia scanner permitted measuring the acoustical anisotropy of reference materials. Taken together, these results document that new methods developed in BioAsset permit a more comprehensive assessment of bone fragility. The set of donor specimens with a documented history of bisphosphonate treatment allows for the assessment of the effects of long-term treatment from the organ down to the tissue and material level. These results will ultimately be linked to the parallel clinical study to provide guidance for determining the optimum duration of bisphosphonate treatment to reduce the incidence of osteoporotic fractures.

Metabolomic and proteomic investigations of impacts of titanium dioxide nanoparticles on Escherichia coli

In a previous study, it was demonstrated that the toxic impact of titanium dioxide nanoparticles on Escherichia coli starts at 10 ppm and is closely related to the presence of little aggregates. It was also assumed that only a part of the bacterial population is able to adapt to this stress and attempts to survive. Proteomic analyses, supported by results from metabolomics, reveal that exposure of E. coli to nano-TiO2 induces two main effects on bacterial metabolism: firstly, the up-regulation of proteins and the increase of metabolites related to energy and growth metabolism; secondly, the down-regulation of other proteins resulting in an increase of metabolites, particularly amino acids. Some proteins, e.g. chaperonin 1 or isocitrate dehydrogenase, and some metabolites, e.g. phenylalanine or valine, might be used as biomarkers of nanoparticles stress. Astonishingly, the ATP content gradually rises in relation with the nano-TiO2 concentration in the medium, indicating a dramatic release of ATP by the damaged cells. These apparently contradictory results accredit the thesis of a heterogeneity of the bacterial population. This heterogeneity is also confirmed by SEM images which show that while some bacteria are fully covered by nano-TiO2, the major part of the bacterial population remains free from nanoparticles, resulting in a difference of proteome and metabolome. The use of combined-omics has allowed to better understand the heterogeneous bacterial response to nano-TiO2 stress due to heterogeneous contacts between the protagonists under environmental conditions.

Cement augmentation versus extended dorsal instrumentation in the treatment of osteoporotic vertebral fractures: a biomechanical comparison

AIMS

Loosening of pedicle screws is a major complication of posterior spinal stabilisation, especially in the osteoporotic spine. Our aim was to evaluate the effect of cement augmentation compared with extended dorsal instrumentation on the stability of posterior spinal fixation.

MATERIALS AND METHODS

A total of 12 osteoporotic human cadaveric spines (T11-L3) were randomised by bone mineral density into two groups and instrumented with pedicle screws: group I (SHORT) separated T12 or L2 and group II (EXTENDED) specimen consisting of T11/12 to L2/3. Screws were augmented with cement unilaterally in each vertebra. Fatigue testing was performed using a cranial-caudal sinusoidal, cyclic (1.0 Hz) load with stepwise increasing peak force.

RESULTS

Augmentation showed no significant increase in the mean cycles to failure and fatigue force (SHORT p = 0.067; EXTENDED p = 0.239). Extending the instrumentation resulted in a significantly increased number of cycles to failure and a significantly higher fatigue force compared with the SHORT instrumentation (EXTENDED non-augmented + 76%, p < 0.001; EXTENDED augmented + 87%, p < 0.001).

CONCLUSION

The stabilising effect of cement augmentation of pedicle screws might not be as beneficial as expected from biomechanical pull-out tests. Lengthening the dorsal instrumentation results in a much higher increase of stability during fatigue testing in the osteoporotic spine compared with cement augmentation. Cite this article: Bone Joint J 2016;98-B:1099-1105.

Quantification of material loss from the neck piece taper junctions of a bimodular primary hip prosthesis. A retrieval study from 27 failed Rejuvenate bimodular hip arthroplasties

The early failure and revision of bimodular primary total hip arthroplasty prostheses requires the identification of the risk factors for material loss and wear at the taper junctions through taper wear analysis. Deviations in taper geometries between revised and pristine modular neck tapers were determined using high resolution tactile measurements. A new algorithm was developed and validated to allow the quantitative analysis of material loss, complementing the standard visual inspection currently used. The algorithm was applied to a sample of 27 retrievals (in situ from 2.9 to 38.1 months) of the withdrawn Rejuvenate modular prosthesis. The mean wear volumes on the flat distal neck piece taper was 3.35 mm(3) (0.55 to 7.57), mainly occurring in a characteristic pattern in areas with high mechanical loading. Wear volume tended to increase with time to revision (r² = 0.423, p = 0.001). Implant and patient specific data (offset, stem size, patient's mass, age and body mass index) did not correlate with the amount of material loss observed (p > 0.078). Bilaterally revised implants showed higher amounts of combined total material loss and similar wear patterns on both sides. The consistent wear pattern found in this study has not been reported previously, suggesting that the device design and materials are associated with the failure of this prosthesis.

Effects of parathyroid hormone on cortical porosity, non-enzymatic glycation and bone tissue mechanics in rats with type 2 diabetes mellitus

Type 2 diabetes mellitus increases skeletal fragility; however, the contributing mechanisms and the efficacy of bone-forming agents are unclear. We studied diabetes and parathyroid hormone (PTH) treatment effects on cortical porosity (Ct.Po), non-enzymatic glycation (NEG) and bone mechanics in Zucker diabetic fatty (ZDF) rats. Eleven-week old ZDF diabetic (DB) and non-diabetic (ND) rats were given 75μg/kg PTH (1-84) or vehicle 5days per week over 12weeks. The right femora and L4 vertebrae were excised, micro-CT scanned, and tested in 3-point bending and uniaxial compression, respectively. NEG of the samples was determined using fluorescence. Diabetes increased Ct.Po (vertebra (vert): +40.6%, femur (fem): +15.5% vs. ND group, p<0.05) but had no effect on NEG. PTH therapy reduced vertebral NEG in the ND animals only (-73% vs untreated group, p<0.05), and increased femoral NEG in the DB vs. ND groups (+63%, p<0.05). PTH therapy had no effect on Ct.Po. Diabetes negatively affected bone tissue mechanics where reductions in vertebral maximum strain (-22%) and toughness (-42%) were observed in the DB vs. ND group (p<0.05). PTH improved maximum strain in the vertebra of the ND animals (+21%, p<0.05) but did not have an effect in the DB group. PTH increased femoral maximum strain (+21%) and toughness (+28%) in ND and decreased femoral maximum stress (-13%) and toughness (-27%) in the DB animals (treated vs. untreated, p<0.05). Ct.Po correlated negatively with maximum stress (fem: R=-0.35, p<0.05, vert: R=-0.57, p<0.01), maximum strain (fem: R=-0.35, p<0.05, vert: R=-0.43, p<0.05) and toughness (fem: R=-0.34, p<0.05, vert: R=-0.55, p<0.01), and NEG correlated negatively with toughness at the femur (R=-0.34, p<0.05) and maximum strain at the vertebra (R=-0.49, p<0.05). Diabetes increased cortical porosity and reduced bone mechanics, which were not improved with PTH treatment. PTH therapy alone may worsen diabetic bone mechanics through formation of new bone with high AGEs cross-linking. Optimal treatment regimens must address both improvements of bone mass and glycemic control in order to successfully reduce diabetic bone fragility. This article is part of a Special Issue entitled "Bone and diabetes".

Biomechanical modelling of impact-related fracture characteristics and injury patterns of the cervical spine associated with riding accidents

BACKGROUND

Horse-related injuries are manifold and can involve the upper and lower limbs, the trunk, spine or head. Cervical spine injuries are not among the most common injuries. However, they can be fatal and often result in neurological symptoms. This study investigated the influence of the posture of the cervical spine on the ultimate strength and the pattern of vertebrae failure with the aim to provide some guidance for protective clothing design.

METHODS

Eighteen human cervical spines, each divided into two specimens (three vertebrae each), were subjected to a simulator test designed to mimic a spinal trauma in different postures of the specimen (neutral, flexion, extension). The stress-to-failure, the deformation at the time of fracture and the fracture patterns assessed based on CT scans were analysed.

FINDINGS

Stress-to-failure of the superior specimens was lower for the flexion group compared to the others (P=0.027). The superior specimens demonstrated higher stress-to-failure in comparison to the inferior specimens (P<0.001). Compression in a neutral or flexed position generated mild or moderate fracture patterns. On the contrary, the placement of the spine in extension resulted in severe fractures mostly associated with narrowing of the spinal canal.

INTERPRETATION

The results imply that a neutral cervical spine position during an impaction can be beneficial. In this position, the failure loads are high, and even if a vertebral fracture occurs, the generated injury patterns are expected to be mild or moderate.

Nuclear spin noise in NMR revisited

The theoretical shapes of nuclear spin-noise spectra in NMR are derived by considering a receiver circuit with finite preamplifier input impedance and a transmission line between the preamplifier and the probe. Using this model, it becomes possible to reproduce all observed experimental features: variation of the NMR resonance linewidth as a function of the transmission line phase, nuclear spin-noise signals appearing as a "bump" or as a "dip" superimposed on the average electronic noise level even for a spin system and probe at the same temperature, pure in-phase Lorentzian spin-noise signals exhibiting non-vanishing frequency shifts. Extensive comparisons to experimental measurements validate the model predictions, and define the conditions for obtaining pure in-phase Lorentzian-shape nuclear spin noise with a vanishing frequency shift, in other words, the conditions for simultaneously obtaining the spin-noise and frequency-shift tuning optima.

Spectral narrowing of Yb:YAG waveguide lasers through hybrid integration with ultrafast laser written Bragg gratings

Laser written waveguides in crystalline materials can be used to make highly efficient, high gain lasers. The bi-directional emission from such lasers however is typically broadband with poor spectral control. Hybridizing a tapered, mode matched laser written Bragg grating with a broadband Yb:YAG crystalline waveguide laser, we demonstrate single longitudinal mode output from one end of the device. Careful control of the grating characteristics led to laser thresholds below 90 mW, slope efficiencies greater than 42% and output powers greater than 20 mW.

The role of patient-mode high-resolution peripheral quantitative computed tomography indices in the prediction of failure strength of the elderly women's thoracic vertebral body

The correlations between the failure load of 20 T12 vertebral bodies, their patient-mode high-resolution peripheral quantitative computed tomography (HR-pQCT) indices, and the L1 areal bone mineral density (aBMD) were investigated. For the prediction of the T12 vertebral failure load, the T12 HR-pQCT microarchitectural parameters added significant information to that of L1 aBMD and to that of cortical BMD, but not to that of T12 vertebral BMD and not to that of T12 trabecular BMD.

INTRODUCTION

HR-pQCT is a new in vivo imaging technique for assessing the three-dimensional microarchitecture of cortical and trabecular bone at the distal radius and tibia. But little is known about this technique in the direct measurement of vertebral body.

METHODS

Twenty female donors with the mean age of 80.1 (7.6) years were included in the study. Dual X-ray absorptiometry of the lumbar spine and femur was performed. The spinal specimens (T11/T12/L1) were dissected, scanned using HR-pQCT scanner, and mechanically tested under 4° wedge compression. The L1 aBMD, T12 patient-mode HR-pQCT indices, and T12 vertebral failure loads were analyzed.

RESULTS

For the prediction of vertebral failure load, the inclusion of BV/TV into L1 aBMD was the best model (R (2) = 0.52), Tb.N and Tb.Sp added significant information to the L1 aBMD and to the cortical BMD, but none of the vertebral microarchitectural parameters yielded additional significant information to the trabecular BMD (or BV/TV) and to the vertebral BMD.

CONCLUSION

Vertebral microarchitectural parameters obtained from the patient-mode HR-pQCT analysis provide significant information on bone strength complementary to that of aBMD and to that of cortical BMD, but not to that of vertebral BMD and not to that of trabecular BMD.

On the tuning of high-resolution NMR probes

Three optimum conditions for the tuning of NMR probes are compared: the conventional tuning optimum, which is based on radio-frequency pulse efficiency, the spin noise tuning optimum based on the line shape of the spin noise signal, and the newly introduced frequency shift tuning optimum, which minimizes the frequency pushing effect on strong signals. The latter results if the radiation damping feedback field is not in perfect quadrature to the precessing magnetization. According to the conventional RLC (resistor-inductor-capacitor) resonant circuit model, the optima should be identical, but significant deviations are found experimentally at low temperatures, in particular on cryogenically cooled probes. The existence of different optima with respect to frequency pushing and spin noise line shape has important consequences on the nonlinearity of spin dynamics at high polarization levels and the implementation of experiments on cold probes.

Continuous-wave Pr³⁺:BaY₂F₈ and Pr³⁺:LiYF₄ lasers in the cyan-blue spectral region

We report on the first, to the best of our knowledge, continuous-wave quasi three-level lasers emitting in the cyan-blue spectral range in praseodymium-doped crystalline materials. Applying Pr(3+):BaY2F8 as an active medium, up to 201 mW of output power at 495 nm could be obtained with a slope efficiency of 27% under pumping with an optically pumped semiconductor laser (2ω-OPSL) at 480 nm. In the same pumping scheme using Pr(3+):LiYF4, output powers up to 70 mW were realized at 491 and 500 nm, respectively. With Pr(3+):BaY2F8, diode-pumped laser operation with up to 11% slope efficiency and 44 mW output power was also achieved. In the latter case, detailed investigations on the temperature dependency of the laser output were conducted. Moreover, comparative experiments were carried out for the first time, to the best of our knowledge, with green-emitting Pr(3+):BaY2F8 lasers at 524 and 553 nm both under diode and 2ω-OPSL excitation.

Development of a dynamic model for ventral hernia mesh repair

Introduction

The adequate way of mesh fixation in laparoscopic ventral hernia repair is still subject to debate. So far, simulation has only been carried out in a static way, thereby omitting dynamic effects of coughing or vomiting. We developed a dynamic model of the anterior abdominal wall.

Materials and methods

An aluminium cylinder was equipped with a pressure controlled, fluid-filled plastic bag, simulating the abdominal viscera. A computer-controlled system allowed the control of influx and efflux, thus creating pressure peaks of up to 200 mmHg to simulate coughing and 290 mmHg to simulate vomiting. We tested fixation with tacks (Absorbatack, Covidien Deutschland, Neustadt a. D., Germany). The model was controlled for the friction coefficient of the tissue against the mesh and the physiologic elasticity of the abdominal wall surrogate.

Results

The model was able to create pressure peaks equivalent to physiologic coughs or vomiting. Physiologic elasticity was thereby maintained. We could show that the friction coefficient is crucial to achieve a physiologic situation.

The meshes showed a tendency to dislocate with an increasing number of coughs (Fig. 4). Nevertheless, when applied in a plain manner, the meshes withstood more cough cycles than when applied with a bulge as in laparoscopic surgery.

Conclusions

The dynamic movement of the abdominal wall, the friction between tissue and mesh and the way of mesh application are crucial factors that have to be controlled for in simulation of ventral abdominal hernia closure. We could demonstrate that patient specific factors such as the frequency of coughing as well as the application technique influence the long term stability of the mesh.

[Substance abuse and pregnancy from an obstetric point of view]

INTRODUCTION

In Germany we find about 2 000 newborns per year with a mother misusing drugs. It is to be feared that there is a substantial amount of underreported substance abuse in pregnant women. To care for these pregnancies from an obstetric point of view as well as from an addiction treatment point of view is a challenge for all health-care professionals, due to multiple drugs being used and the special psychosocial and health issues these mothers and babies -present.

METHOD

A selective search was undertaken in Pubmed, retrieving reviews and original articles from 2001-2013, with consideration of statements, recommendations and guidelines from national and international associations and committees on the topic. This review is intended to assist gynaecologists, obstetricians and paediatricians during the complex peripartum care for the drug abusing pregnant patient.

RESULTS

When offering obstetric care for these pregnancies, several issues have to be taken into account: the special psychological situation of the pregnant drug user, with frequent occurrence of psychiatric comorbidities like depression and anxiety disorders, as well as gynaecological complications like premature labour, intrauterine growth restriction and maternal infectious diseases. The pharmacological complexity of the substances abused and the possible side-effects on the foetus have to be explained to the mother. Maintenance medication for foetomaternal risk reduction and maternal stabilisation remains the state-of-the-art treatment. Furthermore, it is important to explain the neonatal abstinence syndrome to the mother as well as the result of breast-feeding in the presence of smoking and/or infectious diseases.

DISCUSSION

Professionalism and empathy are needed from gynaecologists in order to achieve risk reduction for mother and child in substance-using pregnancies. However, in spite of close cooperation of all health-care professionals and avoidance of stigma, it will be difficult to offer good obstetric care to the high-risk patients with poly-drug abuse.

Increase in facet joint loading after nucleotomy in the human lumbar spine

Low-back pain has been related to degenerative changes after nucleotomy. Although several etiologies for pain after nucleotomy have been proposed, there is evidence of pain arising in the facet joints in general, which may be related to changes in load transfer. This study addresses the effect of nucleotomy on facet joint loading. Nine human lumbar motion segments (age: 40-59 years) were loaded in axial compression and extension-flexion. Reaction forces were compared with soft tissue structures sequentially removed. After nucleotomy the facets supported significantly greater load, almost doubling from a median of 8.6% of the applied external force to 15.8%. Force transmission related to the capsular ligament increased significantly from an intact median of 1.2-5.1% after nucleotomy. No correlation was observed between force increase on the facets and the proportion of disc nucleus removed. Even a small quantity of nucleus removal (range: 0.7-1.7g) increased the forces transmitted over the facet joints, both with and without capsular ligaments. This suggests that the proportion of material removed might not be important clinically with regard to facet joint degeneration and pain.

Efficient visible laser operation of Pr,Mg:SrAl12O19 channel waveguides

We report the fabrication and visible laser operation of Pr,Mg:SrAl12O19 waveguides. Waveguiding structures were created by focusing the radiation of a femtosecond Ti:sapphire laser into bulk material. Guiding losses were determined to be as low as 0.12 dB cm(-1) at 632.8 nm. By employing a frequency-doubled optically pumped semiconductor laser, waveguide laser operation was realized at wavelengths of 525.3, 644.0, and 724.9 nm with output powers as high as 36, 1065, and 504 mW, respectively. To the best of our knowledge this is the first demonstration of green laser operation in a Pr(3+)-doped crystalline waveguide laser.

Reduction of complement factor H binding to CLL cells improves the induction of rituximab-mediated complement-dependent cytotoxicity

A main effector mechanism of rituximab (RTX) is the induction of complement-dependent cytotoxicity (CDC). However, this effector function is limited, because CLL cells are protected from complement-induced damage by regulators of complement activation (RCAs). A prominent RCA in fluid phase is factor H (fH), which has not been investigated in this context yet. Here, we show that fH binds to CLL cells and that human recombinant fH-derived short-consensus repeat 18–20 (hSCR18–20) interferes with this binding. In complement-based lysis assays, CLL cells from therapy-naive patients were differently susceptible to RTX-induced CDC and were defined as CDC responder or CDC non-responder, respectively. In CDC responders, but notably also in non-responders, hSCR18–20 significantly boosted RTX-induced CDC. Killing of the cells was specific for CD20⁺ cells, whereas CD20⁻ cells were poorly affected. CDC resistance was independent of expression of the membrane-anchored RCAs CD55 and CD59, although blocking of these RCAs further boosted CDC. Thus, inhibition of fH binding by hSCR18–20 sensitizes CLL cells to CDC and may provide a novel strategy for improving RTX-containing immunochemotherapy of CLL patients.