Laser-processed diffractive lenses for the frequency range of 4.7 THz.

The development of diffractive lenses for the upper terahertz (THz) frequency range above 1 THz was successfully demonstrated by employing a direct laser ablation (DLA) technology. Two types of samples such as the Soret zone plate lens and the multi-level phase-correcting Fresnel lens were fabricated of a metal foil and crystalline silicon, respectively. The focusing performance along the optical axis of a 4.745 THz quantum cascade laser beam with respect to the positioning angle of the sample was studied by using a real-time microbolometric camera. A binary-phase profile sample demonstrated the values of the focusing gain and focused beam size up to 25 dB and 0.15 mm (2.4λ), respectively. The increase of the phase quantization level to eight led to higher (up to 29 dB) focusing gain values without a measurable increase of optical losses. All the samples were tolerant to misalignment as large as 10 deg of oblique incidence with a focusing power drop no larger than 10%. The results pave the way for new applications of industry-ready DLA technology in the entire THz range.

Real-time gas sensing based on optical feedback in a terahertz quantum-cascade laser.

We report on real-time gas sensing with a terahertz quantum-cascade laser (QCL). The method is solely based on the modulation of the external cavity length, exploiting the intermediate optical feedback regime. While the QCL is operated in continuous-wave mode, optical feedback results in a change of the QCL frequency as well as its terminal voltage. The first effect is exploited to tune the lasing frequency across a molecular absorption line. The second effect is used for the detection of the self-mixing signal. This allows for fast measurement times on the order of 10 ms per spectrum and for real-time measurements of gas concentrations with a rate of 100 Hz. This technique is demonstrated with a mixture of D2O and CH3OD in an absorption cell.

Efficacy and Clinical Utility of a High-Attenuation Object Artifact Reduction Algorithm in Flat-Detector Image Reconstruction Compared With Standard Image Reconstruction.

OBJECTIVE: To evaluate the effectiveness and clinical utility of a metal artifact reduction (MAR) image reconstruction algorithm for the reduction of high-attenuation object (HAO)-related image artifacts. METHODS: Images were quantitatively evaluated for image noise (noiseSD and noiserange) and qualitatively for artifact severity, gray-white-matter delineation, and diagnostic confidence with conventional reconstruction and after applying a MAR algorithm. RESULTS: Metal artifact reduction reduces noiseSD and noiserange (median [interquartile range]) at the level of HAO in 1-cm distance compared with conventional reconstruction (noiseSD: 60.0 [71.4] vs 12.8 [16.1] and noiserange: 262.0 [236.8] vs 72.0 [28.3]; P < 0.0001). Artifact severity (reader 1 [mean ± SD]: 1.1 ± 0.6 vs 2.4 ± 0.5, reader 2: 0.8 ± 0.6 vs 2.0 ± 0.4) at level of HAO and diagnostic confidence (reader 1: 1.6 ± 0.7 vs 2.6 ± 0.5, reader 2: 1.0 ± 0.6 vs 2.3 ± 0.7) significantly improved with MAR (P < 0.0001). Metal artifact reduction did not affect gray-white-matter delineation. CONCLUSIONS: Metal artifact reduction effectively reduces image artifacts caused by HAO and significantly improves diagnostic confidence without worsening gray-white-matter delineation.

High-spectral-resolution terahertz imaging with a quantum-cascade laser.

We report on a high-spectral-resolution terahertz imaging system operating with a multi-mode quantum-cascade laser (QCL), a fast scanning mirror, and a sensitive Ge:Ga detector. By tuning the frequency of the QCL, several spectra can be recorded in 1.5 s during the scan through a gas cell filled with methanol (CH3OH). These experiments yield information about the local absorption and the linewidth. Measurements with a faster frame rate of up to 3 Hz allow for the dynamic observation of CH3OH gas leaking from a terahertz-transparent tube into the evacuated cell. In addition to the relative absorption, the local pressure is mapped by exploiting the effect of pressure broadening.

Direct detection of atomic oxygen on the dayside and nightside of Venus.

Atomic oxygen is a key species in the mesosphere and thermosphere of Venus. It peaks in the transition region between the two dominant atmospheric circulation patterns, the retrograde super-rotating zonal flow below 70 km and the subsolar to antisolar flow above 120 km altitude. However, past and current detection methods are indirect and based on measurements of other molecules in combination with photochemical models. Here, we show direct detection of atomic oxygen on the dayside as well as on the nightside of Venus by measuring its ground-state transition at 4.74 THz (63.2 µm). The atomic oxygen is concentrated at altitudes around 100 km with a maximum column density on the dayside where it is generated by photolysis of carbon dioxide and carbon monoxide. This method enables detailed investigations of the Venusian atmosphere in the region between the two atmospheric circulation patterns in support of future space missions to Venus.

Digital Sequence Information between Benefit-Sharing and Open Data.

Currently, parties to the Convention on Biological Diversity (CBD) are negotiating a strategic plan to save biodiversity. One crucial element of an agreement is the question of whether and how digital sequence information (DSI) is subject to access and benefit-sharing from the utilization of genetic resources, one main instrument of the CBD. In the EU, the Open Data Directive (ODD) of 2019 and the recently adopted Data Governance Act (DGA) already cover research data and to some extent DSI. An analysis of the ODD and the DGA throws a spotlight on the legal uncertainty of utilizing DSI and reveals systemic tensions between open data principles and benefit-sharing restrictions on non-commercial use. It also suggests that a future benefit-sharing mechanism for DSI should avoid distinguishing between commercial and non-commercial use upstream, but should instead favor a solution, which imposes benefit-sharing obligations further downstream or outside of the DSI life cycle.

Functional analyses indicate a pathogenic role of factor H autoantibodies in atypical haemolytic uraemic syndrome.

BACKGROUND: Atypical haemolytic uraemic syndrome (aHUS) is associated with defective complement regulation. Recently, an autoimmune aHUS form has been described that is associated with complement factor H (CFH) autoantibodies. The aim of this study was to address the pathologic relevance of CFH autoantibodies in aHUS. METHODS: CFH autoantibodies were identified and antibody levels were analysed in three aHUS patients during the disease course by the ELISA method. Epitope mapping was performed using recombinant factor H fragments and domain-mapped monoclonal antibodies. The effect of the antibodies on cell-protective activity of CFH was measured by haemolytic assays. CFH:autoantibody complexes were analysed by ELISA. RESULTS: All three autoantibodies bound to the C-terminal domain of CFH, which is essential for CFH binding to cell surfaces. In patient 1, plasma exchanges and immune adsorption temporarily reduced the autoantibody titre and led to temporary clinical improvement. In patient 2, plasma exchanges and long-term immunosuppression strongly reduced the CFH autoantibody level, and induced a stable remission of aHUS. Patient 3 had lower autoantibody levels that decreased during the follow-up and is in good clinical condition. The patients' plasma samples caused enhanced lysis of sheep erythrocytes, and the degree of lysis correlated with the CFH autoantibody titre and the amount of CFH:autoantibody complexes. An addition of purified CFH to aHUS plasma or removal of IgG inhibited the haemolytic activity. CONCLUSION: These results support a direct role of the autoantibodies in aHUS pathology by inhibiting the regulatory function of CFH at cell surfaces and suggest that reduction of the autoantibody titre is beneficial for the patients.

Deletion of complement factor H-related genes CFHR1 and CFHR3 is associated with atypical hemolytic uremic syndrome.

Atypical hemolytic uremic syndrome (aHUS) is associated with defective complement regulation. Disease-associated mutations have been described in the genes encoding the complement regulators complement factor H, membrane cofactor protein, factor B, and factor I. In this study, we show in two independent cohorts of aHUS patients that deletion of two closely related genes, complement factor H-related 1 (CFHR1) and complement factor H-related 3 (CFHR3), increases the risk of aHUS. Amplification analysis and sequencing of genomic DNA of three affected individuals revealed a chromosomal deletion of approximately 84 kb in the RCA gene cluster, resulting in loss of the genes coding for CFHR1 and CFHR3, but leaving the genomic structure of factor H intact. The CFHR1 and CFHR3 genes are flanked by long homologous repeats with long interspersed nuclear elements (retrotransposons) and we suggest that nonallelic homologous recombination between these repeats results in the loss of the two genes. Impaired protection of erythrocytes from complement activation is observed in the serum of aHUS patients deficient in CFHR1 and CFHR3, thus suggesting a regulatory role for CFHR1 and CFHR3 in complement activation. The identification of CFHR1/CFHR3 deficiency in aHUS patients may lead to the design of new diagnostic approaches, such as enhanced testing for these genes.

The Challenging Clinical Management of Patients with Cranial Dural Arteriovenous Fistula and Secondary Parkinson's Syndrome: Pathophysiology and Treatment Options.

Cranial dural arteriovenous fistula (cDAVF) may rarely lead to parkinsonism and rapid cognitive decline. Dysfunction of the extrapyramidal system and the thalamus, due to venous congestion of the Galenic system with subsequent parenchymal edema, is likely to represent an important pathophysiological mechanism. Here, we report a case of a 57-year-old man with a cDAVF of the straight sinus (Borden type III; DES-Zurich bridging vein shunt [BVS] type with direct, exclusive, and strained leptomeningeal venous drainage [LVD]) and subsequent edema of both thalami, the internal capsule, the hippocampi, the pallidum, and the mesencephalon. Several attempts at venous embolization were unsuccessful, and the neurological condition of the patient further deteriorated with progressive parkinsonism and intermittent episodes of loss of consciousness (KPS 30). A suboccipital mini-craniotomy was performed and the culminal vein was disconnected from the medial tentorial sinus, achieving an immediate fistula occlusion. Three-month follow-up MRI revealed complete regression of the edema. Clinically, parkinsonism remitted completely, allowing for tapering of dopaminergic medication. His cognition markedly improved in further course. The purpose of this report is to highlight the importance of rapid and complete cDAVF occlusion to reverse venous hypertension and prevent progressive clinical impairment. The review of the literature underlines the high morbidity and mortality of these patients. Microsurgical disconnection of the fistula plays an important role in the management of these patients and, surprisingly, has not been reported so far.

Histological comparison between laser microtome sections and ground specimens of implant-containing tissues.

Evaluation of bone regeneration and peri-implant bone apposition can only be accomplished using laboratory techniques that allow assessment of decalcified hard tissue. It is known that 5-15µm thick sections can be prepared with the cutting-grinding technique, but their production causes a high material loss (≥0.5mm) between two sections and requires years of training and experience. With the development of the laser microtome it has become possible to cut decalcified bone without high sample material loss. Many scientific publications deal with the application possibilities of the individual methods So far, there is no comparison work between the cutting-grinding technique and laser microtomy. For this reason, new tissue sections were prepared by laser microtome and analyzed histologically from samples that had been previously been prepared by the cutting-grinding technique. Using both methods, it could be demonstrated that the different implants were completely surrounded by a connective tissue layer. In sections (50-100µm) produced by the routine cutting-grinding technique, magnifications up to 20× revealed no detailed histological information because cell structures could not be clearly identified. By contrast, laser microtome sections (10µm) revealed these information as e.g. osteocytes are already clearly visible at 10× magnification. Furthermore, the interface between implant and the surrounding bone could be clearly demonstrated due to visible demarcation between a capsule and connective tissue. At the histological level, laser microtome sections were clearly superior at thicknesses ≥30µm compared to sections produced by the cutting-grinding technique. In addition, laser microtomy has the advantages of time saving and markedly reduced sample loss, especially in cases of the production of serial sections.

Growth factor-mediated augmentation of long bones: evaluation of a BMP-7 loaded thermoresponsive hydrogel in a murine femoral intramedullary injection model.

BACKGROUND: Due to our aging population, an increase in proximal femur fractures can be expected, which is associated with impaired activities of daily living and a high risk of mortality. These patients are also at a high risk to suffer a secondary osteoporosis-related fracture on the contralateral hip. In this context, growth factors could open the field for regenerative approaches, as it is known that, i.e., the growth factor BMP-7 (bone morphogenetic protein 7) is a potent stimulator of osteogenesis. Local prophylactic augmentation of the proximal femur with a BMP-7 loaded thermoresponsive hydrogel during index surgery of an osteoporotic fracture could be suitable to reduce the risk of further osteoporosis-associated secondary fractures. The present study therefore aims to test the hypothesis if a BMP-7 augmented hydrogel is an applicable carrier for the augmentation of non-fractured proximal femurs. Furthermore, it needs to be shown that the minimally invasive injection of a hydrogel into the mouse femur is technically feasible. METHODS: In this study, male C57BL/6 mice (n = 36) received a unilateral femoral intramedullary injection of either 100 µl saline, 100 µl 1,4 Butan-Diisocyanat (BDI)-hydrogel, or 100 µl hydrogel loaded with 1 µg of bone morphogenetic protein 7. Mice were sacrificed 4 and 12 weeks later. The femora were submitted to high-resolution X-ray tomography and subsequent histological examination. RESULTS: Analysis of normalized CtBMD (Cortical bone mineral density) as obtained by X-ray micro-computed tomography analysis revealed significant differences depending on the duration of treatment (4 vs 12 weeks; p < 0.05). Furthermore, within different anatomically defined regions of interest, significant associations between normalized TbN (trabecular number) and BV/TV (percent bone volume) were noted. Histology indicated no signs of inflammation and no signs of necrosis and there were no cartilage damages, no new bone formations, or new cartilage tissues, while BMP-7 was readily detectable in all of the samples. CONCLUSIONS: In conclusion, the murine femoral intramedullary injection model appears to be feasible and worth to be used in subsequent studies that are directed to examine the therapeutic potential of BMP-7 loaded BDI-hydrogel. Although we were unable to detect any significant osseous effects arising from the mode or duration of treatment in the present trial, the effect of different concentrations and duration of treatment in an osteoporotic model appears of interest for further experiments to reach translation into clinic and open new strategies of growth factor-mediated augmentation.

Applying XTT, WST-1, and WST-8 to human chondrocytes: A comparison of membrane-impermeable tetrazolium salts in 2D and 3D cultures.

BACKGROUND: Tetrazolium-based assays are optimized to assess proliferation/toxicity of monolayer or suspension cells in microtiter plates. With regard to tissue engineering and regenerative medicine the need for in vivo like 3D microtissues has an increasing relevance. Applying tetrazolium-based assays to 3D culture systems is technically more challenging. The composed microenvironment may influence the assay standards, e.g. equal distribution of tetrazolium. OBJECTIVE: Evaluation of membrane-impermeable tetrazolium salt-based assays with regard to spheroid culture (3D) of human chondrocytes. METHODS: Chondrocytes were isolated from human articular cartilage. XTT, WST-1, and WST-8 were applied to monolayer cells (2D, varying cell numbers) and spheroids (3D, different sizes) in 96well plates. Formazan formation was measured spectrophotometrically after different incubation periods. Evaluation was done using phase contrast microsopy (toxicity), analyzing the correlation of cell number and absorbance signals (Gompertz function), and document signal over background ratio. RESULTS: In monolayer culture the assays showed a correlation between seeded cell numbers and absorption data. Spheroid sizes are directly related to the starting cell number. A correlation between size and absorbance was only detectable starting from 10,000 cells/aggregate. Phase contrast microscopy of monolayer cells revealed strong toxicity effects of the WST-1 (4 h) and XTT (8 h) assay and no signs of toxicity using WST-8. CONCLUSION: The WST-8 assay is non-toxic and revealed the highest sensitivity in comparison to the XTT or WST-1 assay. There is evidence, that only cells of the outer rim of spheroids are able to convert membrane-impermeable tetrazolium salts to formazans.

Dynamic Cervical Implant versus Anterior Cervical Diskectomy and Fusion: A Prospective Study of Clinical and Radiologic Outcome.

Objective To evaluate clinical and radiologic outcome in patients treated with a dynamic cervical implant (DCI) or anterior cervical diskectomy and fusion (ACDF). Study Design A prospective comparative cohort study. Methods The study included 60 patients with one- or two-level cervical degenerative disk disease (DDD) undergoing treatment with either DCI (n = 30) or ACDF (n = 30). Clinical and radiologic outcomes were assessed 3 and 12 months after surgery. Clinical scoring systems included the Visual Analog Scale for Neck (VAS-N) and Arm pain (VAS-A), the Neck Pain and Disability Scale (NPAD), and the European Quality of Life Scale (EQ-5D). Results Both the DCI and ACDF group showed significant clinical improvement 12 months after surgery using the VAS-N (p = 0.034 and p < 0.001, respectively), VAS-A (p < 0.001 and p < 0.001, respectively), NPAD (p < 0.001 and p < 0.001, respectively), and EQ-5D (p < 0.001 and p < 0.001, respectively). There were no significant differences in clinical outcome comparing both groups at the 3- and 12-month follow-up. The fusion rate at 12 months after surgery was 39.4% and 80.0% in the DCI and ACDF groups, respectively. Radiolucency was found in 90.9% in the DCI group at 12-month follow-up. Conclusion The clinical results for DCI treatment are equivalent to those for ACDF in the treatment of one- and two-level cervical DDD at 12 months after surgery. Further studies are necessary to investigate the high rates of radiolucency and fusion associated with DCI treatment.

Introducing Interlaminar Full-Endoscopic Lumbar Diskectomy: A Critical Analysis of Complications, Recurrence Rates, and Outcome in View of Two Spinal Surgeons' Learning Curves.

Background and Study Objective Interlaminar full-endoscopic diskectomy is a minimally invasive surgical alternative to microdiskectomy for the treatment of lumbar disk herniation. The authors analyze their surgical results and learning curves during and after the introductory phase of this surgical technique. Patients and Methods We present a case review of 76 patients operated on using interlaminar full-endoscopic diskectomy. We retrospectively analyzed two spinal surgeons' learning curves in terms of operation time with respect to intraoperative blood loss, conversion rates, complications, infections, length of hospitalization, need for rehabilitation, recurrence rates, pain intensity, and opioid use. Patients' functional status and Health-related Quality of Life were assessed by follow-up questionnaires for 47 patients, using the North American Spine Society Score and the Short Form 12 in addition to long-term pain intensity, work capacity, and patient satisfaction with the operation. Results A steady state of the learning curve (operation time) of an experienced spinal surgeon was reached after 40 cases. Supervision by a more experienced surgeon can shorten the learning curve. The rate of conversions (10%), complications (5%), and recurrent lumbar disk herniations (28%) did not negatively affect the long-term outcome in patients operated on before and after the learning phase. Patient satisfaction was high. Conclusions The rate of conversions, complications, and recurrent lumbar disk herniations compared with microdiskectomy combined with the challenging learning curve should be considered before surgeons adopt this procedure. Supervision by an endoscopically experienced spinal surgeon during the introductory phase is highly advisable.

FHR-4A: a new factor H-related protein is encoded by the human FHR-4 gene.

We describe a new member of the human Factor H protein family, termed Factor H-related protein 4A (FHR-4A). The corresponding cDNA sequence was isolated and encodes a secreted protein of 559 amino acids, with a predicted molecular weight of 63.2 kDa. Apparently, this novel cDNA is derived from the human FHR-4 gene. Genetic analysis shows that the human FHR-4 gene is composed of 10 coding exons, and two distinct mRNA transcripts are derived from this gene by alternative splicing. The short FHR-4B form represents a truncated variant and encodes a secreted protein of five domains (previously termed FHR-4). The long transcript encodes the novel FHR-4A protein that is composed of nine complement control protein (CCP) domains. A unique feature of FHR-4A is the tandem arrangement of four CCP domains forming a 'natural dimer' of the short isoform. The FHR-4A protein is identified in human plasma as a 86 kDa protein. The difference between the predicted and observed molecular masses is explained by glycosylation. Comparison of the deduced protein sequence of FHR-4A with peptides from a 86 kDa apolipoprotein described by us earlier suggests that the long form, FHR-4A, represents this apoprotein. In summary, FHR-4A is a new Factor H-related protein with a unique domain composition, that is, an internal duplication of four CCP domains. To our knowledge, FHR-4A provides the first evidence for alternative splicing among Factor H-related genes.

Reversible pure word deafness due to inferior colliculi compression by a pineal germinoma in a young adult.

We report a clinical case of a 19-year-old male patient who developed pure word deafness due to the local compressive effect of a pineal germinoma on the inferior colliculi of the quadrigeminal plate. After percutaneous radiation therapy the size of the tumor decreased significantly, while audiometry demonstrated a complete regression of the auditory deficit. Since pure word deafness is commonly attributed to temporal lesions, the inferior colliculi represent an exceptional site for these symptoms. The pathophysiological background and the scarce literature on pure word deafness, especially the one related to neoplasms of the tectal region, are briefly discussed.

3D imaging of transition metals in the zebrafish embryo by X-ray fluorescence microtomography.

Synchrotron X-ray fluorescence (SXRF) microtomography has emerged as a powerful technique for the 3D visualization of the elemental distribution in biological samples. The mechanical stability, both of the instrument and the specimen, is paramount when acquiring tomographic projection series. By combining the progressive lowering of temperature method (PLT) with femtosecond laser sectioning, we were able to embed, excise, and preserve a zebrafish embryo at 24 hours post fertilization in an X-ray compatible, transparent resin for tomographic elemental imaging. Based on a data set comprised of 60 projections, acquired with a step size of 2 µm during 100 hours of beam time, we reconstructed the 3D distribution of zinc, iron, and copper using the iterative maximum likelihood expectation maximization (MLEM) reconstruction algorithm. The volumetric elemental maps, which entail over 124 million individual voxels for each transition metal, revealed distinct elemental distributions that could be correlated with characteristic anatomical features at this stage of embryonic development.

Fluoride concentration in dentine as a biomarker of fluoride intake in European roe deer (Capreolus capreolus) - an electron-microprobe study.

OBJECTIVE: Fluoride concentration in dentine has been recommended as the best marker for the level of chronic fluoride intake and the most suitable indicator of an individual's total body burden of fluoride. We analysed fluoride concentrations in the dentine of cheek teeth of European roe deer from fluoride-polluted habitats to retrospectively assess the level of fluoride uptake into the tissue. Thereby, we tested the hypothesis of the existence of mechanisms that limit fluoride intake of individuals and fluoride exposure of forming dental hard tissues during the late foetal and early postnatal periods in the species. DESIGN: Using electron-microprobe analysis, fluoride profiles were obtained on sectioned P(4)s, M(1)s, and M(3)s from individuals exhibiting pronounced dental fluorosis. Fluoride concentrations were compared between early formed (peripheral) and late-formed (juxtapulpal) dentine both within single teeth and amongst the three different teeth studied. RESULTS: Peripheral dentine of the M(1), which is formed during the late foetal and early postnatal periods, exhibited markedly lower fluoride concentrations than juxtapulpal dentine of the same tooth and both, peripheral and juxtapulpal dentine of P(4) and M(3) that are formed post-weaning. CONCLUSIONS: Our study provides strong support for the hypothesis that in the European roe deer the prenatal and early postnatal (pre-weaning) stages of dental development are (largely) protected against exposure to excess fluoride. This is attributed to the operation of certain protective mechanisms during these periods.

Dentin abnormalities in cheek teeth of wild red deer and roe deer from a fluoride-polluted area in Central Europe.

This study analyses the severity and distribution of mineralization defects in the dentin of red and roe deer teeth (mandibular fourth premolars, first and third molars) obtained from individuals that had lived in a fluoride-polluted area along the Czech-German border. Mineralization defects presented as hypomineralized or interglobular dentin. In the P(4)s and M(3)s the entire dentin exhibited areas of defective mineralization, whereas in the M(1)s only the central and inner dentin portions were affected. This suggests that the early periods of dentin formation in the first molar, occurring during the late fetal and early postnatal (milk-feeding) periods of life, are protected against exposure to excess fluoride levels. Our findings are consistent with the hypothesis that certain protective mechanisms (partial placental diffusion barrier and blood-milk barrier to fluoride, clearance of fluoride from plasma by the rapidly growing skeleton) operate during these ontogenetic periods. Studying fluoride-induced dentin abnormalities in addition to enamel fluorosis broadens the time window during which fluoride effects on the developing dental hard tissues can be recorded. Including dentin in the analysis of dental fluorosis allows a more detailed reconstruction of lifetime fluoride exposure than would be possible by studying enamel fluorosis only, thereby adding to the significance of free-ranging deer as bioindicators of fluoride pollution.