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Purpose: Subretinal (SR) injection in porcine models is a promising avenue for preclinical evaluation of cell and gene therapies. Targeting of the subretinal fluid compartment (bleb) is critical to the procedure, especially if treatment of the cone-rich area centralis is required (i.e., visual streak [VS] in pigs). To our knowledge, this study is the first to investigate the influence of injection site placement on VS involvement in the pig eye., Methods: We performed 23-gauge pars plana vitrectomy followed by SR injection in 41 eyes of 21 animals (Sus scrofa domesticus). In 27 eyes (65.9%), the injection site was placed superior to the VS, and in 14 eyes (34.1%) it was placed inferior to it. Using intraoperative imaging, blebs were classified based on their propagation behavior relative to the VS., Results: In 79% of cases, blebs from inferior injection sites developed away from the VS, exhibiting a mean ± SEM vertical anisotropy (AP) of 0.67 ± 0.11. In contrast, blebs from superior injection sites tended to develop toward the VS with an AP of 1.27 ± 0.18 (P = 0.0070). Blebs developed away from the VS in only 41% of injections (P = 0.0212). Inferior blebs were orientated close to 0° (horizontal), whereas superior blebs displayed varied orientations with a mean angle of 56° (P = 0.0008)., Conclusions: Bleb propagation was anisotropic (i.e., directionally biased) and dependent on injection site placement. Superior injection sites led to superior VS detachment. Morphological analysis suggested increased adhesion forces at the VS and superior vascular arcades. This study will aid the planning of surgeries for targeted subretinal delivery in pig models.

Purpose of Study: Total joint replacements (TJR) have become the cornerstone of modern orthopedic surgery. A great majority of TJR employs ultrahigh molecular weight polyethylene (UHMWPE) liners. TJR manufacturers use many different types of UHMWPE, which are modified by various combinations of crosslinking, thermal treatment, sterilization and/or addition of biocompatible stabilizers. The UHMWPE modifications are expected to improve the polymer's resistance to oxidative degradation and wear (release of microparticles from the polymer surface). This manuscript provides an objective, non-commercial comparison of current UHMWPE formulations currently employed in total knee replacements., Materials and Methods: UHMWPE liners from 21 total knee replacements (TKR) were collected which represent the most implanted liners in the Czech Republic in the period 2020-2021. The UHMWPEs were characterized using several methods: infrared microspectroscopy (IR), non-instrumented and instrumented microindentation hardness testing (MH and MHI), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and solubility measurements. The above-listed methods yielded quite complete information about the structure and properties of each UHMWPE type, including its potential long-term oxidation resistance., Results: For each UHMWPE liner, IR yielded information about immediate oxidative degradation (in the form of oxidation index, OI), level of crosslinking (trans-vinylene index, VI) and crystallinity (CI). The MH and MHI testing gave information about the impact of structure changes on mechanical properties. The remaining methods (DSC, TGA, and solubility measurements) provided additional information regarding the structure changes and resistance to long-term oxidative degradation. Statistical evaluation showed significant differences among the samples as well as interesting correlations among the UHMWPE modifications, structural changes, and mechanical performance., Discussion: Surprisingly enough, UHMWPE materials from different manufacturers showed quite different properties, including the resistance against the long-term oxidative degradation, which is regarded as one of the main reasons of TJR failures. The most promising UHMWPE types were crosslinked materials with biocompatible stabilizers., Conclusions: Current UHMWPE liners from different manufactures used in total knee replacements exhibit significantly different structure and properties. From the point of view of clinical practice, the traditional UHMWPE types, which contained residual radicals from irradiation and/or gamma sterilization, showed inferior resistance to oxidative degradation and should be avoided. The best properties were observed in modern UHMWPE types, which combined crosslinking, biocompatible stabilizers, and sterilization by ethylenoxide or gas plasma., Key Words: UHMWPE; knee replacements; oxidative degradation; infrared spectroscopy; microhardness.

PURPOSE OF THE STUDY In clinical practice UHMWPE is the most commonly used material for manufacturing articular components of joint replacements. The purpose of this study is to find out whether repeated ethylene oxide sterilization results in oxidative degradation of UHMWPE or not and also whether the oxidative degradation of various types of ethylene oxide-sterilized UHMWPE depends on storage time or not. MATERIAL AND METHODS The set included 12 samples of UHMWPE (three samples with different modifications (virgin PE, with E vitamin and cross-linked with thermal treatment) and different number of sterilizations (0×-3×)). The set also included 8 samples of commercial components of hip or knee replacements sterilized with ethylene oxide and stored for different storage periods. The oxidative degradation was assessed by infrared microspectroscopy, based on which the oxidation index (OI), transvinylene index (VI), crystallinity index (CI) and E vitamin index (EI) were calculated. Mechanical properties of UHMWPE were obtained through microhardness measurements. Statistical processing of the results was performed. RESULTS In all the samples, very low oxidative degradation values were reported (most OI values < 0.1). All radiation crosslinked UHMWPE samples showed an increased VI index and a slightly lower crystallinity index. All unmodified samples (irrespective of whether or not and how many times or how long ago the samples were sterilized with EtO) had almost zero value of VI. Changes in crystallinity were negligible (in the rage of 0.56-0.63), which required very accurate measurements of micromechanical properties. Yet, linear correlation was established between microhardness and crystallinity. DISCUSSION All the mentioned indices changed as anticipated: OIs were very low and slightly increased with time of storage, VIs of radiation crosslinked samples grew in proportion to the total gama radiation dose, CIs decreased in samples thermally treated by remelting, and EIs were very low due to negligible concentration of stabiliser (0.1%) in the samples of medical grade UHMWPE. CONCLUSIONS All samples showed zero or minimum oxidative degradation. This confirmed that neither ethylene oxide sterilization, nor multiple EtO sterilization or longer storage of polymer after ethylene oxide sterilization result in major oxidative degradation. Key words: UHMWPE, ethylene oxide, sterilization, oxidation, infrared spectroscopy, microhardness.

At the end of the nineteenth century, the imperial capital of the k.k. Danube monarchy, Vienna, enabled the meeting of two important figures in medical history: the surgeon Eduard Albert (1841-1900) and his student Adolf Lorenz (1854-1946). Both men had comparable traits: they came from humble backgrounds, were exceptionally talented and longed for a career in the supreme medical discipline-surgery. Both achieved the highest goals in their disciplines but the spectrum of their interests was much broader. The life of both and their contacts to each other are reported here. In this respect the Memorial Book of House No. 528 by Eduard Albert in Senftenberg was also evaluated.

Adolf Lorenz, the founder of orthopedics in Austria and father of the later Nobel laureate Konrad Lorenz, and the founder and first president of the Czechoslovak Republic, Tomáš G. Masaryk, were in contact. In the seventies and eighties of the nineteenth century both studied at the University of Vienna: Masaryk, four years older, Philosophy and Lorenz Medicine. The first meetings took place in the dissecting room of the Anatomical Institute. Later both entered (scientific) careers and became well-known personalities. Almost 40 years after the first coincidental encounter, Lorenz remembered his former student, meanwhile president of the Czechoslovak Republic, and made contact with him. The correspondence kept in the Masaryk Institute in Prague will be presented here.

Gravitational-wave emission can lead to the coalescence of close pairs of compact objects orbiting each other 1,2 . In the case of neutron stars, such mergers may yield masses above the Tolman-Oppenheimer-Volkoff limit (2 to 2.7 solar masses) 3 , leading to the formation of black holes 4 . For white dwarfs, the mass of the merger product may exceed the Chandrasekhar limit, leading either to a thermonuclear explosion as a type Ia supernova 5,6 or to a collapse forming a neutron star 7,8 . The latter case is expected to result in a hydrogen- and helium-free circumstellar nebula and a hot, luminous, rapidly rotating and highly magnetized central star with a lifetime of about 10,000 years 9,10 . Here we report observations of a hot star with a spectrum dominated by emission lines, which is located at the centre of a circular mid-infrared nebula. The widths of the emission lines imply that wind material leaves the star with an outflow velocity of 16,000 kilometres per second and that rapid stellar rotation and a strong magnetic field aid the wind acceleration. Given that hydrogen and helium are probably absent from the star and nebula, we conclude that both objects formed recently from the merger of two massive white dwarfs. Our stellar-atmosphere and wind models indicate a stellar surface temperature of about 200,000 kelvin and a luminosity of about 10 4.6 solar luminosities. The properties of the star and nebula agree with models of the post-merger evolution of super-Chandrasekhar-mass white dwarfs 9 , which predict a bright optical and high-energy transient upon collapse of the star 11 within the next few thousand years. Our observations indicate that super-Chandrasekhar-mass white-dwarf mergers can avoid thermonuclear explosion as type Ia supernovae, and provide evidence of the generation of magnetic fields in stellar mergers.

Subluminous Type Ia supernovae, such as the Type Iax-class prototype SN 2002cx, are described by a variety of models such as the failed detonation and partial deflagration of an accreting carbon-oxygen white dwarf star or the explosion of an accreting, hybrid carbon-oxygen-neon core. These models predict that bound remnants survive such events with, according to some simulations, a high kick velocity. We report the discovery of a high proper motion, low-mass white dwarf (LP 40-365) that travels at a velocity greater than the Galactic escape velocity and whose peculiar atmosphere is dominated by intermediate-mass elements. Strong evidence indicates that this partially burnt remnant was ejected following a subluminous Type Ia supernova event. This supports the viability of single-degenerate supernova progenitors., (Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Polyhydroxyalkanoic acids (PHAs) are natural polyesters that can be used to produce bioplastics which are biodegradable. Numerous microorganisms accumulate PHAs as energy reserves. Combinations of different PHAs monomers lead to the production of bioplastics with very different properties. In the present work, we show the capability of strains belonging to various phylogenetic lineages within the genus Mesorhizobium, isolated from Lotus corniculatus nodules, to produce different PHA monomers. Among our strains, we found the production of 3-hydroxybutyrate, 3-hydroxyvalerate, 3-hydroxydodecanoate, and 3-hydroxyhexadecanoate. Most of the PHA-positive strains were phylogenetically related to the species M. jarvisii. However, our findings suggest that the ability to produce different monomers forming PHAs is strain-dependent.