The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. ...Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystalline graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic samples only. Our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.
To detect environmental factors, which may be possible risk factors in the disease course of Fuchs' endothelial corneal dystrophy (FECD). Evaluation of patients with FECD registered in the FECD ...genetics database of the Center for Ophthalmology, University Hospital Cologne. For the evaluation, disease onset, central corneal thickness, best spectacle corrected visual acuity (BSCVA, logMAR), and modified Krachmer grading (grades 1-6) were correlated with the presence of diabetes mellitus (DM), body mass index (BMI), and smoking behavior. To put the age-related increase in Krachmer grading into perspective, a correction of grading were formed. Depending on the variables studied, differences between groups were examined by Mann-Whitney U test and chi-square test. The significance level was 5%. 403 patients with FECD were included in the analysis. The mean age of the patients was 70.0 ± 10.32 (range 28-96) years. The mean age at diagnosis of those patients was 63.1 ± 13.2 years. The female-to-male ratio was 1.46:1. Patients with a BMI > 30.0 kg/m
developed FECD significantly earlier than patients with a BMI < 30 kg/m
, p = 0.001. Patients with DM showed significantly more often an Krachmer grade of 5, p = 0.015. Smoking had a negative effect on Krachmer grading (p = 0.024). Using the mediation analysis, the presence of DM correlated Krachmer Grade 5 (p = 0.015), and the presence of DM correlated with BMI > 30.0 kg/m
(p = 0.012). In addition to smoking and DM our study shows for the first time that obesity may have a negative impact on the development of FECD. Whether dietary interventions and hormones can influence the development or progression of the disease needs to be investigated in future studies.
Glioblastoma is a malignant brain tumor with mean overall survival of less than 15 months. Blood vessel leakage and peritumoral edema lead to increased intracranial pressure and augment neurological ...deficits which profoundly decrease the quality of life of glioblastoma patients. It is unknown how the dynamics of cerebrospinal fluid (CSF) turnover are affected during this process. By monitoring the transport of CSF tracers to the systemic blood circulation after infusion into the cisterna magna, we demonstrate that the outflow of CSF is dramatically reduced in glioma-bearing mice. Using a combination of magnetic resonance imaging (MRI) and near-infrared (NIR) imaging, we found that the circulation of CSF tracers was hindered after cisterna magna injection with reduced signals along the exiting cranial nerves and downstream lymph nodes, which represent the major CSF outflow route in mice. Due to blockage of the normal routes of CSF bulk flow within and from the cranial cavity, CSF tracers were redirected into the spinal space. In some mice, impaired CSF clearance from the cranium was compensated by a lymphatic outflow from the sacral spine.
The lymphatic vascular system plays important roles in the control of tissue fluid homeostasis and immune responses. While VEGF-A-induced angiogenesis promotes hair follicle (HF) growth, the ...potential role of lymphatic vessels (LVs) in HF cycling has remained unknown. In this study, we found that LVs are localized in close proximity to the HF bulge area throughout the postnatal and depilation-induced hair cycle in mice and that a network of LVs directly connects the individual HFs. Increased LV density in the skin of K14-VEGF-C transgenic mice was associated with prolongation of anagen HF growth. Conversely, HF entry into the catagen phase was accelerated in K14-sVEGFR3 transgenic mice that lack cutaneous LVs. Importantly, repeated intradermal injections of VEGF-C promoted hair growth in mice. Conditioned media from lymphatic endothelial cells promoted human dermal papilla cell (DPC) growth and expression of IGF-1 and alkaline phosphatase, both activators of DPCs. Our results reveal an unexpected role of LVs in coordinating and promoting HF growth and identify potential new therapeutic strategies for hair loss-associated conditions.
Secondary lymphedema is a common complication after cancer treatment, but the pathomechanisms underlying the disease remain unclear. Using a mouse tail lymphedema model, we found an increase in local ...and systemic levels of the lymphangiogenic factor vascular endothelial growth factor (VEGF)-C and identified CD68+ macrophages as a cellular source. Surprisingly, overexpression of VEGF-C in a transgenic mouse model led to aggravation of lymphedema with increased immune cell infiltration and vascular leakage compared with wild-type littermates. Conversely, blockage of VEGF-C by overexpression of soluble VEGF receptor-3 reduced edema development, diminishing inflammation and blood vascular leakage. Similar findings were obtained in a hind limb lymph node excision lymphedema model. Flow cytometry analyses and immunofluorescence stainings in lymphedematic tissue showed that VEGF receptor-3 expression was restricted to lymphatic endothelial cells. Our data suggest that endogenous VEGF-C causes blood vascular leakage and fluid influx into the tissue, thus actively contributing to edema formation. These data may provide the basis for future clinical therapeutic approaches.
In the advent of affordable photo- and soft-lithography using polydimethylsiloxane (PDMS), low cost multi-step microfabrication methods have become available to a broad scientific community today. ...Although these methods are frequently applied for microfluidic prototype production in academic and industrial settings, fast design iterations and rapid prototyping within a few minutes with a high degree of flexibility are nearly impossible. To reduce microfluidic concept-to-chip time and costs, a number of alternative rapid prototyping techniques have recently been introduced including CNC micromachining, 3D printing and plotting out of numeric CAD designs as well as micro-structuring of thin PDMS sheets and pressure sensitive adhesives. Although micro-structuring of pressure sensitive adhesives promises high design flexibility, rapid fabrication and simple biochip assembly, most adhesives are toxic for living biological systems. Since an appropriate bio-interface and proper biology-material interaction is key for any cell chip and organ-on-a-chip system, only a limited number of medical-grade materials are available for microfluidic prototyping. In this study, we have characterized four functional biomedical-grade pressure sensitive adhesives for rapid prototyping (e.g. less than 1 hour) applications including structuring precision, physical and optical properties as well as biocompatibilities. While similar biocompatibility was found for all four adhesives, significant differences in cutting behavior, bonding strength to glass and polymers as well as gas permeability was observed. Practical applications included stability testing of multilayered, membrane-integrated organ-on-a-chip devices under standard cell culture conditions (e.g. 2-3 weeks at 37 °C and 100% humidity) and a shear-impact up to 5 dynes/cm
. Additionally, time- and shear-dependent uptake of non-toxic fluorescently labelled nanoparticles on human endothelial cells are demonstrated using micro-structured adhesive-bonded devices. Our results show that (a) both simple and complex microdevices can be designed, fabricated and tested in less than 1 hour, (b) these microdevices are stable for weeks even under physiological shear force conditions and (c) can be used to maintain cell monolayers as well as 3D cell culture systems.
Purpose
To evaluate whether and how preoperative visual acuity predicts visual acuity outcome after Descemet Membrane Endothelial Keratoplasty (DMEK).
Methods
One thousand eighty-four out of 1162 ...consecutive eyes having undergone DMEK alone or combined with cataract surgery (triple-DMEK) between July 2011 and February 2016 from the prospective Cologne DMEK database were included and analyzed retrospectively for correlations between pre- and postoperative visual acuity values at 1, 3, 6, and 12 months after transplantation.
Results
There is a significant correlation between pre- and postoperative visual acuity (VA) after (triple)-DMEK after 6 and 12 months (
p
= 0.005 and
p
= 0.011 respectively; Pearson’s correlation coefficient 0.240 and 0.224). Preoperative VA below 20/100 leads to delayed and reduced final visual acuity results after 12 months (
p
< 0.001). However, defining an increase in VA > 0.1 logMAR as clinically relevant, we could not show any clinically relevant significant difference in the time needed to recover to final VA and in final VA. There is no significant difference for preoperative VA values above 20/40. The chance to reach postoperative VA above 20/25 is 40% for preoperative VA of 20/200, 50% for preoperative VA of 20/60 and > 60% for preoperative VA of 20/40.
Conclusion
DMEK results in very good final postoperative visual acuity results even in eyes with very poor preoperative vision caused by corneal pathology. However, preoperative visual acuity values below 20/100 result in significantly poorer visual recovery, which suggests that there is benefit in performing surgery early enough before this value is reached. Preoperative visual acuity seems to be an adjuvant tool for the prediction of the final visual outcome after DMEK.
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