Tunable structure and linear viscoelastic properties of poly(glycerol adipate urethane)-based elastomeric composites for tissue regeneration

Elastomeric biocomposites based on poly(glycerol adipate urethane) and hydroxyapatite were fabricated for tissue regeneration. The poly(glycerol adipate urethane) (PGAU) elastomeric composite matrices were obtained by chemical crosslinking of the poly(glycerol adipate) prepolymer (pPGA) with diisocyanate derivative of L-lysine. Two series of composites varying in the amount of L-lysine diisocyanate ethyl ester (LDI) used as a crosslinking agent were manufactured. As a ceramic filler both unmodified and L-lysine surface-modified hydroxyapatite (HAP) particles were used. The novelty of our research consists in the manufactured elastomeric materials and characterization of their linear viscoelastic (LVE) properties. The LVE properties of the composites were investigated by means of dynamic thermomechanical analysis. Frequency sweep and amplitude sweep measurements were performed in shear mode. The influence of the crosslinking agent (LDI) amount, HAP content and surface modification of HAP on the LVE properties of the composites was determined based on the analysis of the master curves of storage (G') and loss (G″) moduli and of tanδ of the composites. Depending on the amount of LDI, HAP and surface modification, the materials differ in the values of rubber elasticity plateau modulus (G0) and G' and G″ determined at selected shear frequencies and at the glassy state. G0 ranges from 278 kPa to 3.98 MPa, G' in the glassy state is within the range of 219 MPa-459 MPa. The G0 values of the PGAU-based composites are within the stiffness range of soft tissue. In view of the choice of HAP as the ceramic component and the G0 values, elastomeric composites have the potential to be used as filling materials in small bone defects (due to their mechanical similarity to osteoid) as well as materials for cartilage tissue regeneration.

Effect of Poly(Vinyl Pyrrolidone) on Iodine Release from Acrylate-Endcapped Urethane-Based Poly(Ethylene Glycol) Hydrogels as Antibacterial Wound Dressing

Infections are still a major cause of morbidity in burn wounds. Although silver has been used strongly in past centuries as an anti-bacterial, it can lead to allergic reactions, bacterial resistance, and delayed wound healing. Iodine-based antibacterials are becoming an interesting alternative. In this work, the effect of complexation with poly(vinyl pyrrolidone) (PVP) and poly(ethylene oxide) (PEO)-based polymers is explored by using different acrylate-endcapped urethane-based poly(ethylene glycol) (AUP) polymers, varying the molar mass (MM) of the poly(ethylene glycol) (PEG) backbone, with possible addition of PVP. The higher MM AUP outperforms the swelling potential of commercial wound dressings such as Kaltostat, Aquacel Ag, and Hydrosorb and all MM show superior mechanical properties. The addition of iodine to the polymers is compared to Iso-Betadine Tulle (IBT). Interestingly, the addition of PVP does not lead to increased iodine complexation compared to the blank AUP polymers, while all have a prolonged iodine release compared to the IBT, which leads to a burst release. The observed prolonged release also leads to larger inhibition zones during antibacterial tests. Complexing iodine in AUP polymers with or without PVP leads to antimicrobial wound dressings which may hold potential for future application to treat infected wounds.

Raspberry-like PLA/PGS biodegradable microparticles with urethane linkages: Unlocking tailored release of magnesium ions and oxygen for bone tissue engineering

Designing biodegradable microparticles with finely controlled release properties for tissue engineering systems remains a significant scientific challenge. This study introduces a novel approach by fabricating urethane-linked PLA/PGS microparticles loaded with magnesium peroxide. The microparticles offer potential applications in bone tissue engineering due to their ability to provide a controlled release of oxygen and magnesium ions while maintaining physiological pH. The PGS pre-polymer was synthesized via polycondensation and characterized using FTIR, 1H NMR, and GPC. Microparticle morphology transformed from smooth to raspberry-like upon incorporation of PGS, as observed by SEM. Microparticle size was tuned by varying PGS and PLA concentrations. FTIR analysis confirmed the successful formation of urethane links within the microparticles. MgO2-loaded PLA/PGS microparticles exhibited sustained release of dissolved oxygen and magnesium ions for 21 days while maintaining physiological pH better than PLA microparticles. Cell viability assays confirmed microparticle cytocompatibility, and ALP and Alizarin red assays demonstrated their ability to induce osteogenic differentiation. These findings highlight the potential of pH-controlled MgO2-loaded microparticles as an effective system for bone tissue engineering. In conclusion, this study presents a novel approach to designing biodegradable microparticles with adjustable release properties for bone tissue engineering. The urethane-based MgO2-loaded microparticles provide controlled release of oxygen and magnesium ions and regulate the environment's pH, making them a promising system for bone tissue engineering applications.

Hydrogel-Embedded Precision-Cut Lung Slices Model Lung Cancer Premalignancy Ex Vivo

Lung cancer is the leading global cause of cancer-related deaths. Although smoking cessation is the best prevention, 50% of lung cancer diagnoses occur in people who have quit smoking. Research into treatment options for high-risk patients is constrained to rodent models, which are time-consuming, expensive, and require large cohorts. Embedding precision-cut lung slices (PCLS) within an engineered hydrogel and exposing this tissue to vinyl carbamate, a carcinogen from cigarette smoke, creates an in vitro model of lung cancer premalignancy. Hydrogel formulations are selected to promote early lung cancer cellular phenotypes and extend PCLS viability to six weeks. Hydrogel-embedded PCLS are exposed to vinyl carbamate, which induces adenocarcinoma in mice. Analysis of proliferation, gene expression, histology, tissue stiffness, and cellular content after six weeks reveals that vinyl carbamate induces premalignant lesions with a mixed adenoma/squamous phenotype. Putative chemoprevention agents diffuse through the hydrogel and induce tissue-level changes. The design parameters selected using murine tissue are validated with hydrogel-embedded human PCLS and results show increased proliferation and premalignant lesion gene expression patterns. This tissue-engineered model of human lung cancer premalignancy is the foundation for more sophisticated ex vivo models that enable the study of carcinogenesis and chemoprevention strategies.

Functionalisation of lignin with urethane linkages and their strengthening effect on PLA composites

Lignin was functionalised by crosslinking with hexamethylene diisocyanate (HDI) through the heterogenous reaction in the solvent dimethyl sulfoxide for preferential improvement in the mechanical properties of composites. The successful synthesis of lignin modified with HDI was confirmed by the instrumental analyses, e.g., FTIR, XPS, and FESEM. The incorporation of optimum crosslinked lignin in polylactic acid (PLA) matrix was systematically evaluated on the basis of their thermal stability, mechanical property, glass transition temperature (Tg), water contact angle, water absorption, and water permeability. The results displayed that incorporation of fillers had prominent effects on tensile tear strength, which could improve tensile strength up to 231 % and elongation at break up to 53 % due to the good interface compatibility between PLA and modified lignin. Further, with the inclusion of fillers, PLA composites exhibited higher crystallinity in comparison to neat PLA.

Pattern sensitivity of ampakine-hypoxia interactions for evoking phrenic motor facilitation in anesthetized rat

Repeated hypoxic episodes can produce a sustained (>60 min) increase in neural drive to the diaphragm. The requirement of repeated hypoxic episodes (vs. a single episode) to produce phrenic motor facilitation (pMF) can be removed by allosteric modulation of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors using ampakines. We hypothesized that the ampakine-hypoxia interaction resulting in pMF requires that ampakine dosing precedes the onset of hypoxia. Phrenic nerve recordings were made from urethane-anesthetized, mechanically ventilated, and vagotomized adult male Sprague-Dawley rats during isocapnic conditions. Ampakine CX717 (15 mg/kg iv) was given immediately before (n = 8), during (n = 8), or immediately after (n = 8) a 5-min hypoxic episode (arterial oxygen partial pressure 40-45 mmHg). Ampakine before hypoxia (Aprior) resulted in a sustained increase in inspiratory phrenic burst amplitude (i.e., pMF) reaching +70 ± 21% above baseline (BL) after 60 min. This was considerably greater than corresponding values in the groups receiving ampakine during hypoxia (+28 ± 47% above BL, P = 0.005 vs. Aprior) or after hypoxia (+23 ± 40% above BL, P = 0.005 vs. Aprior). Phrenic inspiratory burst rate, heart rate, and systolic, diastolic, and mean arterial pressure (mmHg) were similar across the three treatment groups (all P > 0.3, treatment effect). We conclude that the presentation order of ampakine and hypoxia impacts the magnitude of pMF, with ampakine pretreatment evoking the strongest response. Ampakine pretreatment may have value in the context of hypoxia-based neurorehabilitation strategies.NEW & NOTEWORTHY Phrenic motor facilitation (pMF) is evoked after repeated episodes of brief hypoxia. pMF can also be induced when an allosteric modulator of AMPA receptors (ampakine) is intravenously delivered immediately before a single brief hypoxic episode. Here we show that ampakine delivery before hypoxia (vs. during or after hypoxia) evokes the largest pMF with minimal impact on arterial blood pressure and heart rate. Ampakine pretreatment may have value in the context of hypoxia-based neurorehabilitation strategies.

Nerve Wrap for Local Delivery of FK506/Tacrolimus Accelerates Nerve Regeneration

Peripheral nerve injuries (PNIs) occur frequently and can lead to devastating and permanent sensory and motor function disabilities. Systemic tacrolimus (FK506) administration has been shown to hasten recovery and improve functional outcomes after PNI repair. Unfortunately, high systemic levels of FK506 can result in adverse side effects. The localized administration of FK506 could provide the neuroregenerative benefits of FK506 while avoiding systemic, off-target side effects. This study investigates the utility of a novel FK506-impregnated polyester urethane urea (PEUU) nerve wrap to treat PNI in a previously validated rat infraorbital nerve (ION) transection and repair model. ION function was assessed by microelectrode recordings of trigeminal ganglion cells responding to controlled vibrissae deflections in ION-transected and -repaired animals, with and without the nerve wrap. Peristimulus time histograms (PSTHs) having 1 ms bins were constructed from spike times of individual single units. Responses to stimulus onsets (ON responses) were calculated during a 20 ms period beginning 1 ms after deflection onset; this epoch captures the initial, transient phase of the whisker-evoked response. Compared to no-wrap controls, rats with PEUU-FK506 wraps functionally recovered earlier, displaying larger response magnitudes. With nerve wrap treatment, FK506 blood levels up to six weeks were measured nearly at the limit of quantification (LOQ ≥ 2.0 ng/mL); whereas the drug concentrations within the ION and muscle were much higher, demonstrating the local delivery of FK506 to treat PNI. An immunohistological assessment of ION showed increased myelin expression for animals assigned to neurorrhaphy with PEUU-FK506 treatment compared to untreated or systemic-FK506-treated animals, suggesting that improved PNI outcomes using PEUU-FK506 is mediated by the modulation of Schwann cell activity.

Biodegradation of poly(ester-urethane) coatings by Halopseudomonas formosensis

Impranil® DLN-SD is a poly(ester-urethane) (PEU) that is widely used as coating material for textiles to fine-tune and improve their properties. Since coatings increase the complexity of such plastic materials, they can pose a hindrance for sustainable end-of-life solutions of plastics using enzymes or microorganisms. In this study, we isolated Halopseudomonas formosensis FZJ due to its ability to grow on Impranil DLN-SD and other PEUs as sole carbon sources. The isolated strain was exceptionally thermotolerant as it could degrade Impranil DLN-SD at up to 50°C. We identified several putative extracellular hydrolases of which the polyester hydrolase Hfor_PE-H showed substrate degradation of Impranil DLN-SD and thus was purified and characterized in detail. Hfor_PE-H showed moderate temperature stability (Tm = 53.9°C) and exhibited activity towards Impranil DLN-SD as well as polyethylene terephthalate. Moreover, we revealed the enzymatic release of monomers from Impranil DLN-SD by Hfor_PE-H using GC-ToF-MS and could decipher the associated metabolic pathways in H. formosensis FZJ. Overall, this study provides detailed insights into the microbial and enzymatic degradation of PEU coatings, thereby deepening our understanding of microbial coating degradation in both contained and natural environments. Moreover, the study highlights the relevance of the genus Halopseudomonas and especially the novel isolate and its enzymes for future bio-upcycling processes of coated plastic materials.

Electrospun Poly(carbonate-urea-urethane)s Nonwovens with Shape-Memory Properties as a Potential Biomaterial

Poly(carbonate-urea-urethane) (PCUU)-based scaffolds exhibit various desirable properties for tissue engineering applications. This study thus aimed to investigate the suitability of PCUU as polymers for the manufacturing of nonwoven mats by electrospinning, able to closely mimic the fibrous structure of the extracellular matrix. PCUU nonwovens of fiber diameters ranging from 0.28 ± 0.07 to 0.82 ± 0.12 μm were obtained with an average surface porosity of around 50-60%. Depending on the collector type and solution concentration, a broad range of tensile strengths (in the range of 0.3-9.6 MPa), elongation at break (90-290%), and Young's modulus (5.7-26.7 MPa) at room temperature of the nonwovens could be obtained. Furthermore, samples collected on the plate collector showed a shape-memory effect with a shape-recovery ratio (Rr) of around 99% and a shape-fixity ratio (Rf) of around 96%. Biological evaluation validated the inertness, stability, and lack of cytotoxicity of PCUU nonwovens obtained on the plate collector. The ability of mesenchymal stem cells (MSCs) and endothelial cells (HUVECs) to attach, elongate, and grow on the surface of the nonwovens suggests that the manufactured nonwovens are suitable scaffolds for tissue engineering applications.

Hierarchically Templated Synthesis of 3D-Printed Crosslinked Cyclodextrins for Lycopene Harvesting

Plants produce a wide range of bioactive phytochemicals, such as antioxidants and vitamins, which play crucial roles in aging prevention, inflammation reduction, and reducing the risk of cancer. Selectively harvesting these phytochemicals, such as lycopene, from tomatoes through the adsorption method is cost-effective and energy efficient. In this work, a templated synthesis of 3D-printed crosslinked cyclodextrin polymers featuring nanotubular structures for highly selective lycopene harvesting is reported. Polypseudorotaxanes formed by triethoxysilane-based telechelic polyethylene glycols and α-cyclodextrins (α-CDs) are designed as the template to (1) synthetically access urethane-based nanotubular structures at the molecular level, and (2) construct 3D-printed architectures with designed macroscale voids. The polypseudorotaxane hydrogels showed good rheological properties for direct ink writing, and the 3D-printed hydrogels were converted to the desired α-CD polymer network through a three-step postprinting transformation. The obtained urethane-crosslinked α-CD monoliths possess nanotubular structures and 3D-printed voids. They selectively adsorb lycopene from raw tomato juice, protecting lycopene from photo- or thermo-degradations. This work highlights the hierarchically templated synthesis approach in developing functional 3D-printing materials by connecting the bottom-up molecular assembly and synthesis with the top-down 3D architecture control and fabrication.

CAR1 as a new selective marker for genetic engineering of wine yeasts

A common problem in engineering industrial yeasts, and wine yeasts in particular, is the lack or scarcity of selective markers for introducing desired genetic changes. Almost all such markers, which are usually auxotrophic mutations, would reduce the growth characteristics of yeast strains. However, a potentially useful marker could be the CAR1 gene encoding arginase, the deletion of which reduces the accumulation of the carcinogen ethyl carbamate in wine, making such a deletion beneficial for wine production and maintainable in wine yeast strains. Here we demonstrate the use of the CAR1 gene as a selective marker. First, we observe that complete deletion of CAR1 in a triploid wine strain of Saccharomyces cerevisiae causes strong growth inhibition on a medium containing arginine as the only nitrogen source. Then, we show that strains with CAR1 deletion can be reliably transformed using CAR1 as a plasmid marker. Thus, the CAR1 gene can be used as a convenient selective marker in genetic engineering of wine yeasts, in particular using CRISPR/Cas9 technology.

Time-restricted feeding affects the fecal microbiome metabolome and its diurnal oscillations in lung cancer mice

The homeostasis of the gut microbiota and circadian rhythm is critical to host health, and both are inextricably intertwined with lung cancer. Although time-restricted feeding (TRF) can maintain circadian synchronization and improve metabolic disorders, the effects of TRF on the fecal microbiome, metabolome and their diurnal oscillations in lung cancer have not been discussed. We performed 16S rRNA sequencing and untargeted metabonomic sequencing of the feces prepared from models of tumor-bearing BALB/c nude mice and urethane-induced lung cancer. We demonstrated for the first time that TRF significantly delayed the growth of lung tumors. Moreover, TRF altered the abundances of the fecal microbiome, metabolome and circadian clocks, as well as their rhythmicity, in lung cancer models of tumor-bearing BALB/c nude mice and/or urethane-induced lung cancer C57BL/6J mice. The results of fecal microbiota transplantation proved that the antitumor effects of TRF occur by regulating the fecal microbiota. Notably, Lactobacillus and Bacillus were increased upon TRF and were correlated with most differential metabolites. Pathway enrichment analysis of metabolites revealed that TRF mainly affected immune and inflammatory processes, which might further explain how TRF exerted its anticancer benefits. These findings underscore the possibility that the fecal microbiome/metabolome regulates lung cancer following a TRF paradigm.

Deformation and Durability of Soft Three-Dimensional-Printed Polycarbonate Urethane Porous Membranes for Potential Use in Pelvic Organ Prolapse

Pelvic organ prolapse (POP) is the herniation of the pelvic organs into the vaginal space, resulting in the feeling of a bulge and organ dysfunction. Treatment of POP often involves repositioning the organs using a polypropylene mesh, which has recently been found to have relatively high rates of complications. Complications have been shown to be related to stiffness mismatches between the vagina and polypropylene, and unstable knit patterns resulting in mesh deformations with mechanical loading. To overcome these limitations, we have three-dimensional (3D)-printed a porous, monofilament membrane composed of relatively soft polycarbonate-urethane (PCU) with a stable geometry. PCU was chosen for its tunable properties as it is comprised of both hard and soft segments. The bulk mechanical properties of PCU were first characterized by testing dogbone samples, demonstrating the dependence of PCU mechanical properties on its measurement environment and the effect of print pathing. The pore dimensions and load-relative elongation response of the 3D-printed PCU membranes under monotonic tensile loading were then characterized. Finally, a fatigue study was performed on the 3D-printed membrane to evaluate durability, showing a similar fatigue resistance with a commercial synthetic mesh and hence its potential as a replacement.

The Induction of Long-Term Potentiation by Medial Septum Activation under Urethane Anesthesia Can Alter Gene Expression in the Hippocampus

We studied changes in the expression of early genes in hippocampal cells in response to stimulation of the dorsal medial septal area (dMSA), leading to long-term potentiation in the hippocampus. Rats under urethane anesthesia were implanted with stimulating electrodes in the ventral hippocampal commissure and dMSA and a recording electrode in the CA1 area of the hippocampus. We found that high-frequency stimulation (HFS) of the dMSA led to the induction of long-term potentiation in the synapses formed by the ventral hippocampal commissure on the hippocampal CA1 neurons. One hour after dMSA HFS, we collected the dorsal and ventral hippocampi on both the ipsilateral (damaged by the implanted electrode) and contralateral (intact) sides and analyzed the expression of genes by qPCR. The dMSA HFS led to an increase in the expression of bdnf and cyr61 in the ipsilateral hippocampi and egr1 in the ventral contralateral hippocampus. Thus, dMSA HFS under the conditions of degeneration of the cholinergic neurons in the medial septal area prevented the described increase in gene expression. The changes in cyr61 expression appeared to be dependent on the muscarinic M1 receptors. Our data suggest that the induction of long-term potentiation by dMSA activation enhances the expression of select early genes in the hippocampus.

Application of multiple ultra-high-pressure homogenization to the pasteurization process of Japanese rice wine, sake

Hiire is a pasteurization process in the production of Japanese rice wine (sake), which stabilizes the quality of product; however, it also generates the carcinogen ethyl carbamate (EC). In this study, we investigated the application of ultra-high-pressure homogenization (UHPH) as an alternative sterilization method for sake production. Microbiological analysis revealed that multiple UHPH treatments sterilized hiochi lactobacilli (Lactobacillus fructivorans, L. homohiochii, L. casei, and L. hilgardii) and Saccharomyces cerevisiae. Enzyme activity assays revealed that α-amylase, glucoamylase, and acid-carboxypeptidase activities were reduced to less than 1% of the levels in non-pasteurized sake after four-time UHPH treatment. These results show that UHPH treatment meets the two requirements of the sake sterilization process sterilization and enzyme inactivation. The UHPH-processed sake did not show any significant changes in general properties but had reduced organic acid and aromatic component contents, with ethyl caproate content showing the most significant reduction of approximately 20%. Interestingly, EC was detected in pasteurized sake but not in UHPH-processed sake. These findings indicate that the UHPH technology could be used to inactivate microorganisms and enzymes in sake without generating EC.

Effect of elastomeric urethane monomer on physicochemical properties and shrinkage stress of resin composites

This study aimed to evaluate the effect of an elastomeric urethane monomer (Exothane-24) in different concentrations on physicochemical properties, gap formation, and polymerization shrinkage stress of experimental resin composites. All experimental composites were prepared with 50 wt.% of Bis-GMA and 50 wt.% of TEGDMA, to which 0 wt.% (control), 10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.% of Exothane-24 were added. Filler particles (65 wt.%) were then added to these resin matrixes. Ultimate tensile strength (UTS: n = 10), flexural strength (FS: n = 10), flexural modulus (FM: n = 10), hardness (H: n = 10), hardness reduction (HR: n = 10), degree of conversion (DC: n = 5), gap width (GW: n = 10), and polymerization shrinkage stress in Class I (SS-I: n = 10) and Class II (SS-II: n = 10) simulated configuration. All test data were analyzed using one-way ANOVA and Tukey's test (α = 0.05;  = 0.2). Exothane-24 in all concentrations decreased the H, HR, DC, GW, SS-I, and SS-II (p < 0.05) without affecting the UTS, and FS (p > 0.05). Reduction in FM was observed only in the Exothane 40% and 30% groups compared to the control (p < 0.05). Exothane-24 at concentrations 20% and 30% seems suitable since it reduced GW and polymerization SS without affecting the properties of the composite resins tested, except for H.

Self-Repairing and Energy-Harvesting Triboelectric Sensor for Tracking Limb Motion and Identifying Breathing Patterns

The increasing prevalence of health problems stemming from sedentary lifestyles and evolving workplace cultures has placed a substantial burden on healthcare systems. Consequently, remote health wearable monitoring systems have emerged as essential tools to track individuals' health and well-being. Self-powered triboelectric nanogenerators (TENGs) have exhibited significant potential for use as emerging detection devices capable of recognizing body movements and monitoring breathing patterns. However, several challenges remain to be addressed in order to fulfill the requirements for self-healing ability, air permeability, energy harvesting, and suitable sensing materials. These materials must possess high flexibility, be lightweight, and have excellent triboelectric charging effects in both electropositive and electronegative layers. In this work, we investigated self-healable electrospun polybutadiene-based urethane (PBU) as a positive triboelectric layer and titanium carbide (Ti3C2Tx) MXene as a negative triboelectric layer for the fabrication of an energy-harvesting TENG device. PBU consists of maleimide and furfuryl components as well as hydrogen bonds that trigger the Diels-Alder reaction, contributing to its self-healing properties. Moreover, this urethane incorporates a multitude of carbonyl and amine groups, which create dipole moments in both the stiff and the flexible segments of the polymer. This characteristic positively influences the triboelectric qualities of PBU by facilitating electron transfer between contacting materials, ultimately resulting in high output performance. We employed this device for sensing applications to monitor human motion and breathing pattern recognition. The soft and fibrous-structured TENG generates a high and stable open-circuit voltage of up to 30 V and a short-circuit current of 4 μA at an operation frequency of 4.0 Hz, demonstrating remarkable cyclic stability. A significant feature of our TENG is its self-healing ability, which allows for the restoration of its functionality and performance after sustaining damage. This characteristic has been achieved through the utilization of the self-healable PBU fibers, which can be repaired via a simple vapor solvent method. This innovative approach enables the TENG device to maintain optimal performance and continue functioning effectively even after multiple uses. After integration with a rectifier, the TENG can charge various capacitors and power 120 LEDs. Moreover, we employed the TENG as a self-powered active motion sensor, attaching it to the human body to monitor various body movements for energy-harvesting and sensing purposes. Additionally, the device demonstrates the capability to recognize breathing patterns in real time, offering valuable insights into an individual's respiratory health.

Measuring oxytocin release in response to gavage: Computational modelling and assay validation

In the present experiments, we tested the conclusion from previous electrophysiological experiments that gavage of sweet food and systemically applied insulin both stimulate oxytocin secretion. To do so, we measured oxytocin secretion from urethane-anaesthetised male rats, and demonstrated a significant increase in secretion in response to gavage of sweetened condensed milk but not isocaloric cream, and a significant increase in response to intravenous injection of insulin. We compared the measurements made in response to sweetened condensed milk with the predictions from a computational model, which we used to predict plasma concentrations of oxytocin from the published electrophysiological responses of oxytocin cells. The prediction from the computational model was very closely aligned to the levels of oxytocin measured in rats in response to gavage.

Somatosensory-Evoked Early Sharp Waves in the Neonatal Rat Hippocampus

The developing entorhinal-hippocampal system is embedded within a large-scale bottom-up network, where spontaneous myoclonic movements, presumably via somatosensory feedback, trigger hippocampal early sharp waves (eSPWs). The hypothesis, that somatosensory feedback links myoclonic movements with eSPWs, implies that direct somatosensory stimulation should also be capable of evoking eSPWs. In this study, we examined hippocampal responses to electrical stimulation of the somatosensory periphery in urethane-anesthetized, immobilized neonatal rat pups using silicone probe recordings. We found that somatosensory stimulation in ~33% of the trials evoked local field potential (LFP) and multiple unit activity (MUA) responses identical to spontaneous eSPWs. The somatosensory-evoked eSPWs were delayed from the stimulus, on average, by 188 ms. Both spontaneous and somatosensory-evoked eSPWs (i) had similar amplitude of ~0.5 mV and half-duration of ~40 ms, (ii) had similar current-source density (CSD) profiles, with current sinks in CA1 strata radiatum, lacunosum-moleculare and DG molecular layer and (iii) were associated with MUA increase in CA1 and DG. Our results indicate that eSPWs can be triggered by direct somatosensory stimulations and support the hypothesis that sensory feedback from movements is involved in the association of eSPWs with myoclonic movements in neonatal rats.

Simultaneous High-Throughput Monitoring of Urethane Reactions Using Near-Infrared Hyperspectral Imaging

High-throughput (HTP) research is becoming more widely utilized due to its advantages in rapid screening of large parameter space. When HTP is used for reaction screening, often only the end products are analyzed by off-line techniques, leaving behind valuable process information. Information-rich spectroscopy tools have remained under-utilized in HTP workflows. In this study, near-infrared (NIR) hyperspectral imaging (HSI) is demonstrated to be a versatile and accurate tool that can simultaneously monitor multiple reactions, opening up future opportunities to maximize information extraction from such HTP reaction screening experiments. Model urethane reactions are used here to demonstrate the concept, and the general approach can be widely applied to any reactions involving NIR-active functional groups. The fast speed and accurate chemical information made possible by NIR HSI are expected be another important addition to the toolkit of HTP research.

Differential Effect of Dopamine D4 Receptor Activation on Low-Frequency Oscillations in the Prefrontal Cortex and Hippocampus May Bias the Bidirectional Prefrontal–Hippocampal Coupling

Dopamine D4 receptor (D4R) mechanisms are implicated in psychiatric diseases characterized by cognitive deficits, including schizophrenia, ADHD, and autism. The cellular mechanisms are poorly understood, but impaired neuronal synchronization in cortical networks was proposed to contribute to these deficits. In animal experiments, D4R activation was shown to generate aberrant increased gamma oscillations and to reduce performance on cognitive tasks requiring functional prefrontal cortex (PFC) and hippocampus (HPC) networks. While fast oscillations in the gamma range are important for local synchronization within neuronal ensembles, long-range synchronization between distant structures is achieved by slow rhythms in the delta, theta, alpha ranges. The characteristics of slow oscillations vary between structures during cognitive tasks. HPC activity is dominated by theta rhythm, whereas PFC generates unique oscillations in the 2–4 Hz range. In order to investigate the role of D4R on slow rhythms, cortical activity was recorded in rats under urethane anesthesia in which slow oscillations can be elicited in a controlled manner without behavioral confounds, by electrical stimulation of the brainstem reticular formation. The local field potential segments during stimulations were extracted and subjected to fast Fourier transform to obtain power density spectra. The selective D4R agonist A-412997 (5 and 10 mg/kg) and antagonists L-745870 (5 and 10 mg/kg) were injected systemically and the peak power in the two frequency ranges were compared before and after the injection. We found that D4R compounds significantly changed the activity of both HPC and PFC, but the direction of the effect was opposite in the two structures. D4R agonist enhanced PFC slow rhythm (delta, 2–4 Hz) and suppressed HPC theta, whereas the antagonist had an opposite effect. Analogous changes of the two slow rhythms were also found in the thalamic nucleus reuniens, which has connections to both forebrain structures. Slow oscillations play a key role in interregional cortical coupling; delta and theta oscillations were shown in particular, to entrain neuronal firing and to modulate gamma activity in interconnected forebrain structures with a relative HPC theta dominance over PFC. Thus, the results of this study indicate that D4R activation may introduce an abnormal bias in the bidirectional PFC–HPC coupling which can be reversed by D4R antagonists.

[Effectiveness of different epidural coverage materials for preventing postoperative scar hyperplasia and dural adhesion in spine]

Objective: To analyze the effects and mechanisms of three commonly used epidural coverings, gelatin sponge, bovine Achilles tendon extract collagen and polyester urethane fiber, in preventing epidural scar adhesions after laminectomy in rats. Methods: Forty-eight adult Wistar rats were excised from L₂ to L₅ lamina to establish laminectomy models, and were divided into four groups with random number table according to different covering materials (12 rats in each group): blank group (group A), gelatin sponge group (absorbable, group B), polyester urethane fiber group (non-absorbable, group C) and bovine Achilles tendon extract collagen group (absorbable, group D). At 4 and 12 weeks postoperatively, the spinal tissues of the operated area were taken for gross observation (Rydell scar adhesion rating criteria) and histological observation (Nussbaum criteria); and the expression of three scar proliferation-related cytokines, basic fibroblast growth factor (bFGF), growth transforming factor β1 (TGF-β1) and vascular endothelial growth factor (VEGF), were measured in the peridural tissues. The differences between the indices in each group were analyzed and compared. Results: All 48 rats survived, and gross and histological findings at 4 and 12 weeks showed no dural adhesions in the gelatin sponge and bovine Achilles tendon extract collagen groups, adhesions in the polyester urethane fiber group, and heavy adhesions and spinal cord compression in the blank control group. There were significant differences in the Rydell grade and Nussbaum histological score between the absorbable material group and the non-absorbable group (both P<0.05). Western protein blotting at 4 and 12 weeks confirmed that the expression levels of three cytokines, including bFGF, TGF-β1, and VEGF, were lower in the absorbable material group than those in the non-absorbable group (all P<0.01). Immunofluorescence tests at 12 weeks confirmed that the expression of bFGF, TGF-β1 and VEGF were all lower in the gelatin sponge group (9.81±0.81, 12.42±2.35, 8.63±1.76) and the bovine Achilles tendon extract collagen group (12.70±2.02, 8.23±1.03, 10.19±2.67) than those in the polyester urethane fiber group (33.94±2.03, 30.29±2.76, 25.79±1.21) (all P<0.01). Conclusions: Bovine achilles tendon extract collagen and gelatin sponge can effectively reduce the hyperplasia of scar and dural adhesions after spinal surgery.

Urethane-Foam-Embedded Silicon Pressure Sensors including Stress-Concentration Packaging Structure for Driver Posture Monitoring

We propose urethane-foam-embedded silicon pressure sensors, including a stress-concentration packaging structure, for integration into a car seat to monitor the driver’s cognitive state, posture, and driving behavior. The technical challenges of embedding silicon pressure sensors in urethane foam are low sensitivity due to stress dispersion of the urethane foam and non-linear sensor response caused by the non-uniform deformation of the foam. Thus, the proposed package structure includes a cover to concentrate the force applied over the urethane foam and frame to eliminate this non-linear stress because the outer edge of the cover receives large non-linear stress concentration caused by the geometric non-linearity of the uneven height of the sensor package and ground substrate. With this package structure, the pressure sensitivity of the sensors ranges from 0 to 10 kPa. The sensors also have high linearity with a root mean squared error of 0.049 N in the linear regression of the relationship between applied pressure and sensor output, and the optimal frame width is more than 2 mm. Finally, a prototype 3 × 3 sensor array included in the proposed package structure detects body movements, which will enable the development of sensor-integrated car seats.

Ethyl carbamate triggers ferroptosis in liver through inhibiting GSH synthesis and suppressing Nrf2 activation

Humans are inevitably exposed to ethyl carbamate (EC) via consumption of fermented food and beverages. EC, known as an environmental toxin, can cause oxidative stress-mediated severe toxicity, but the underlying mechanisms remain unveiled. Ferroptosis is a newly identified ROS-mediated non-apoptotic cell death characterized by iron accumulation and excessive lipid oxidation. In this study, we first found that EC triggered ferroptosis in liver cells by detection of decreased cell viability, GSH, GPX4 and Ferritin levels, as well as increased iron and MDA contents. Ferroptosis inhibitor ferrostatin-1 (Fer-1) pretreatment rescued ferroptotic damage, indicating that ferroptosis was critical for EC-caused cell death. Furthermore, GSH synthesis precursor N-acetylcysteine displayed significant anti-ferroptotic properties and we suggested that GSH depletion might be the main cause of ferroptosis under EC exposure. EC-triggered GSH depletion mainly depended on suppressed GSH synthesis via inhibition of SLC7A11 and GCLC expressions. Notably, EC blocked Nrf2 activation by repression of phosphorylation modification and nuclear translocation, which further resulted in ferroptosis occurrence. We also observed EC-induced liver dysfunction and inflammation, accompanied with oxidative stress, ferroptosis and downregulated Nrf2 signaling in Balb/c mice, which could be effectively reversed by Fer-1 and tBHQ pretreatment. Together, our study indicated that ferroptosis is a new mechanism for EC-caused toxicity, which was attributed to Nrf2 inactivation and GSH depletion.

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Ethyl carbamate (EC) caused ferroptosis in L02 cells and liver tissues.

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GSH depletion was critical for EC-induced ferroptotic cell death.

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EC exposure blocked GSH synthesis-related pathways.

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Inactivation of Nrf2 signaling was involved in EC-triggered ferroptosis.

Synthesis of (Hyper)Branched Monohydroxyl Alkoxysilane Oligomers toward Silanized Urethane Prepolymers

The aim of this work was the synthesis of (hyper)branched oligomers based on trialkoxysilane in various conditions and further application of them in order to modify the urethane prepolymers. Hydroxyl-terminated trialkoxysilane was used as a monomer for homo-condensation. It was obtained by reaction of 3-aminopropyl trialkoxysilane (APTES) with ethylene carbonate (EC). The reaction was based on the attack of amine at the carbonyl carbon atom followed by ring opening of the carbonate to give a urethane (carbamate) product. The next step was the condensation via substitution of ethoxy groups on silicon atom with the terminal hydroxyalkyl groups present in the primary product with the evolution of ethanol. Accordingly, the impact of temperature and type of catalyst on process efficiency was investigated. A quantitative analysis of reaction progress and products of the conversion of EC together with ethanol evolution was conducted by means of gas chromatography, which allowed us to determine the formation of monomeric product and, indirectly, of oligomeric products. It was found that at room temperature after 24 h, the majority of the monomeric product was isolated, whereas at elevated temperature in the presence of Ti-based catalyst, further condensation of the monomer into branched oligomers was preferred, and, moreover, the application of vacuum intensified that process. The obtained products were structurally characterized by ¹H and ²⁹Si NMR, MALDI-ToF and Gel Permeation Chromatography. Finally, two different alkoxysilane products, monomeric and oligomeric, were applied for modification of urethane prepolymer, forming silanized one (SPUR). The influence of the silanizing agent on the mechanical and thermal properties of the moisture-cured products was shown before and after additional conditioning in water.

CRISPR/Cas9-mediated Inactivation of arginase in a yeast strain isolated from Nuruk and its impact on the whole genome

Despite the advantages of CRISPR/Cas9 technology in the food industry, controversy over its off-target effects exists. We engineered an industrial Saccharomyces cerevisiae strain isolated from a Korean rice wine starter, Nuruk, using CRISPR/Cas9 to decrease ethyl carbamate (EC) formation. We disrupted the CAR1 gene encoding arginase, which plays a key role in EC formation. Subsequently, we compared the whole genome of the engineered strain to that of the wild type by analyzing heterozygous and homozygous mutations through variant calling. Homozygous mutations in the genome of the engineered strains were identified as the target mutations in CAR1 induced by CRISPR/Cas9, and no other off-target effects were observed. Our findings have critical implications for the use of CRISRP/Cas9 technology in yeasts in the food industry.

E3 ligase MKRN3 is a tumor suppressor regulating PABPC1 ubiquitination in non-small cell lung cancer

Central precocious puberty (CPP), largely caused by germline mutations in the MKRN3 gene, has been epidemiologically linked to cancers. MKRN3 is frequently mutated in non-small cell lung cancers (NSCLCs) with five cohorts. Genomic MKRN3 aberrations are significantly enriched in NSCLC samples harboring oncogenic KRAS mutations. Low MKRN3 expression levels correlate with poor patient survival. Reconstitution of MKRN3 in MKRN3-inactivated NSCLC cells directly abrogates in vitro and in vivo tumor growth and proliferation. MKRN3 knockout mice are susceptible to urethane-induced lung cancer, and lung cell-specific knockout of endogenous MKRN3 accelerates NSCLC tumorigenesis in vivo. A mass spectrometry-based proteomics screen identified PABPC1 as a major substrate for MKRN3. The tumor suppressor function of MKRN3 is dependent on its E3 ligase activity, and MKRN3 missense mutations identified in patients substantially compromise MKRN3-mediated PABPC1 ubiquitination. Furthermore, MKRN3 modulates cell proliferation through PABPC1 nonproteolytic ubiquitination and subsequently, PABPC1-mediated global protein synthesis. Our integrated approaches demonstrate that the CPP-associated gene MKRN3 is a tumor suppressor.

New Thermal Latent Catalyst Using Titanium and Organic Ligand for Urethane Polymerization

New thermal-latent metal catalyst such as tetrakis (lauorate) titanium (LPTi) was designed and synthesized based on a lauroyl peroxide and titanium. The synthetic method is simple with one step reaction. LPTi structure was confirmed by FT-IR analysis, also nano-sized structure of LPTi confirmed using SEM-EDX. LPTi is thermal-latent metal catalyst including titanium that not only promotes urethane synthesis reaction but also increases the dissociation rate of blocked isocyanate. As a result of quantitative analysis of NCO (%) through back titration, when LPTi was added, NCO (%) increased from 2.34% to 3.24%. LPTi can be used as an excellent catalyst for urethane reaction by reducing the polymerization time by about 30% compared to no catalyst. LPTi can be applied to the electronic polymer synthesis.

Development of a sensitive non-competitive immunoassay via immunocomplex binding peptide for the determination of ethyl carbamate in wine samples

Ethyl carbamate is a group of 2A carcinogen ubiquitously existed in fermented foods. The monitoring of its residues was important for evaluating the potential risk to human beings. Immunoassays with good accuracy and simplicity are great analytical tools for small molecule contaminants. However, it is typically confined in a competitive mode for small molecules with drawback of the sensitivity curbing. In this work, three different phages displayed peptides with capability of identifying the xanthyl ethyl carbamate immunocomplex were isolated from phage library. The binding mechanism of peptides and immunocomplex was studied by computer-assisted simulation. Results indicated that the xanthydrol group of xanthyl ethyl carbamate and the Asn-32 and Asn-92 residues of the antibody light chain were mainly responsible for binding. Simultaneously, a sensitive non-competitive immunoassay for detecting ethyl carbamate in wine samples was developed. The established method exhibited a limit of detection of 5.4 ng/mL and a linear range from 8.7 ng/mL to 32 ng/mL for wine samples. In comparison with the conventional competitive immunoassay, the sensitivity of the proposed non-competitive immunoassay was improved by 17-fold. The results of the immunoassay were validated by a standard ultra-performance liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometry, which illustrated good reliability of the proposed assay.

Polycarbonate Urethane Mesh: A New Material for Pelvic Reconstruction

OBJECTIVE

Polycarbonate urethane (PCU) is a new biomaterial, and its mechanical properties can be tailored to match that of vaginal tissue. We aimed to determine whether vaginal host immune and extracellular matrix responses differ after PCU versus lightweight polypropylene (PP) mesh implantation.

METHODS

Hysterectomy and ovariectomy were performed on 24 Sprague-Dawley rats. Animals were divided into 3 groups: (1) PCU vaginal mesh, (2) PP vaginal mesh, and (3) sham controls. Vagina-mesh complexes or vaginas (controls) were excised 90 days after surgery. We quantified responses by comparing: (1) histomorphologic scoring of hematoxylin and eosin- and Masson trichrome-stained slides, (2) macrophage subsets (immunolabeling), (3) pro-inflammatory and anti-inflammatory cytokines (Luminex panel), (4) matrix metalloproteinase (MMP)-2 and -9 using an enzyme-linked immunosorbent assay, and (5) type I/III collagen using picrosirius red staining.

RESULTS

There was no difference in histomorphologic score between PCU and PP (P = 0.211). Although the histomorphologic response was low surrounding all mesh fibers, groups with PCU and PP mesh had a higher histomorphologic score than the control group (P < 0.005 and P < 0.002, respectively). There were no differences between groups in terms of macrophage subsets, pro-inflammatory cytokines, anti-inflammatory cytokines, MMP-2 and MMP-9, or collagen ratio.

CONCLUSIONS

Polycarbonate urethane, an elastomer with material properties similar to those of vaginal tissue, elicits minimal host inflammatory responses in a rat model. Because its implantation does not elicit more inflammation than currently used lightweight PP, using PCU for prolapse mesh warrants further investigation with larger animal models.

Chemical hazards in grapes and wine, climate change and challenges to face

Climate change has an impact on the chemical risks associated to wine consumption related with grape development and microbial contamination. We can classify chemical hazards in wine into two groups: those present in grapes due to agricultural practices, environmental contamination or fungal growth and those coming from fermentation and the winemaking process. The first group includes mycotoxins, whilst the second encompasses ethyl carbamate, biogenic amines, sulfur dioxide and proteins used as technological ingredients such as fining material. Usually the effective control of chemical hazards is achieved by assuring that they either are minimized or absent in the final product since their removal is somewhat difficult and sometimes it may affect sensory properties, which is a major issue in wine. Interestingly, it is possible to give recommendations to avoid excess of these compounds, but more research is needed to face future challenges related to climate change and consumer demands.

Nanocrystalline hydroxyapatite-poly(thioketal urethane) nanocomposites stimulate a combined intramembranous and endochondral ossification response in rabbits

Resorbable bone cements are replaced by bone osteoclastic resorption and osteoblastic new bone formation near the periphery. However, the ideal bone cement would be replaced by new bone through processes similar to fracture repair, which occurs through a variable combination of endochondral and intramembranous ossification. In this study, nanocrystalline hydroxyapatite (nHA)-poly(thioketal urethane) (PTKUR) cements were implanted in femoral defects in New Zealand White rabbits to evaluate ossification at 4, 12, and 18 months. Four formulations were tested: an injectable, flowable cement and three moldable putties with varying ratios of calcium phosphate to sucrose granules. New bone formation and resorption of the cement by osteoclasts occurred near the periphery. Stevenel's Blue and Safranin O staining revealed infiltration of chondrocytes into the cements and ossification of the cartilaginous intermediate. These findings suggest that nHA-PTKUR cements support combined intramembranous and endochondral ossification, resulting in enhanced osseointegration of the cement that could potentially improve patient outcomes.

Effect of the addition of thiourethane oligomers on the sol⿿gel composition of BisGMA/TEGDMA polymer networks

OBJECTIVES

Thiourethane oligomers have been shown to increase the fracture toughness and reduce the polymerization stress of methacrylate-based materials. However, network formation has not been elucidated in these materials yet. The aim of this study was to evaluate how the addition of a thiourethane oligomer (TU) influences the sol/gel composition and network structure of methacrylate-based materials using dynamic mechanical analysis and extraction methods.

MATERIALS AND METHODS

BisGMA/TEGDMA at systematically varied mass ratios (20/80 to 80/20wt%) were mixed with pre-polymerized thiourethane oligomers at 0 (control) or 20wt%, synthesized by combining pentaerythritol tetra-3-mercaptopropionate with dicyclohexylmethane 4,4⿲-Diisocyanate, at 1:2 isocyanate:thiol. 0.1wt% of 2,2-Dimethoxy-2-phenylacetophenone was added as the photoinitiator and 0.3wt% of 2,6-di-tert-butyl-4-methylphenol was added as a free radical inhibitor. Disk specimens (0.8ÿ10mm in diameter, n=3) were photoactivated at 270mW/ (320⿿500nm) for 1min. The degree of conversion (DC) was measured in near-IR (˿6165cm⿿1). Specimens were immersed in two different solvents (water for 7 days or dicholoromethane for 48h). Water sorption (WS) and solubility (SL) were obtained according to ISO 4049. The leachates for both solutions were analyzed with 1H-NMR (400MHz, CDCL3). Bar specimens (1ÿ3ÿ25mm, photocured and then post-processed at 180°C for 8h to DC>95%) were subjected to dynamic mechanical analysis (⿿30 to 230°C) to obtain glass transition temperature (Tg), tan delta curves and crosslinking density (ν). Data was analyzed with two-way ANOVA/Tukey⿿s test (95%).

RESULTS

In general, the presence of TU increased the overall conversion. The WS was similar for all groups, but the SL decreased by 2-fold with the addition of the TU oligomer for all compositions, except BisGMA/TEGDMA 80/20. The BisGMA concentration of the leachates increased with increasing BisGMA in the initial mixture, and with the presence of thiourethane. This compositional drift of the gel with the presence of TU was attributed to the preferential dissolution of TEGDMA into the TU network. Tg and ν decreased with the addition of TU, as expected. The addition of TU produced more homogeneous networks, as evidenced by narrower breadth of the tan delta curve.

CONCLUSION

The addition of TU affected the composition of the sol/gel in crosslinked networks, which were more homogeneous and presented 2-fold less potentially toxic leachates than the methacrylate controls.

CLINICAL SIGNIFICANCE

The addition of TU may produce less cytotoxic materials based on the increased conversion and reduced amount of unreacted extractables from its network after water storage.

Cortical stroke affects activity and stability of theta/delta states in remote hippocampal regions

Cognitive impairment is a common outcome of ischemic stroke. Our previous work has shown that an experimental stroke in the cortex reduces activity in remote hippocampal layers in rats. This study seeks to uncover the underlying functional connections between these areas by analyzing changes to oscillatory activity, signal power, and communication. We induced an ischemic stroke in the left somatosensory cortex of rats and used linear micro-electrode arrays to simultaneously record from cortex and hippocampus under urethane anesthesia at two weeks and one month after stroke. We found significant increase in signal power, as well as an increase in the number of brain state changes in response to stroke. Our results suggest that the cortex modulates the activity and stability of hippocampal oscillations, which is disrupted following cortical stroke that can lead to cognitive impairment.

A Method of Correcting for the Effect of Temperature on Low-Contrast Penetration Measurement in Urethane Phantoms

Urethane-based test objects are routinely used for ultrasound quality assurance because of their durability and robustness. The acoustic properties of these phantoms including speed of sound and attenuation, however, have a strong dependence on temperature. Reliable measurement of low-contrast penetration, which is widely used for ultrasound system quality assurance testing, with these phantoms is therefore problematic. To alleviate this, a correction method was proposed using speed of sound estimated by measuring filament target separation. The method was developed using a range of 17 transducer geometry and frequency combinations across 5 ultrasound systems and validated using a further 5 systems. This was found to reduce the uncertainty of low-contrast penetration measurement from an average 17.6 mm to 4.9 mm over the temperature range 8°C to 32°C. This represents a greater than threefold improvement in precision of low-contrast penetration measurement.

Biomimetic Poly(Poly(ε-caprolactone)-Polytetrahydrofuran urethane) Based Nanofibers Enhanced Chondrogenic Differentiation and Cartilage Regeneration

Scaffolds for stem cell-based therapy of cartilage defect require bioactivity and stiffness mimicking to the native cartilage matrix. In this study, we fabricated electrospun nanofibers composited of cartilage matrix components (collagen or chondroitin sulfate) and poly(ε-caprolactone)-polytetrahydrofuran (PCL-PTHF). PCL-PTHF with rat tail derived collagen was named PR and PCL-PTHF with chondroitin sulfate (PS) termed PS, which have a modulus of 7.5 MPa and 3.6 MPa, respectively, within the range of cartilage matrix. Their chondrogenic potential for guiding chondrogenic differentiation and promoting cartilage regeneration were investigated based upon mesenchymal stem cells (MSCs). Results showed that both PR and PS nanofibers have the ability to induce chondrogenesis of MSCs and accelerate the regeneration of injured cartilage surface, probably via the suppression of Tumor necrosis factor (TNF) signaling pathway as evidenced by microarray profiles. Comparatively, PR showed better chondrogenic potential both in vitro and in vivo than that of PS, which may induce chondrogenesis through Hypoxia inducing factor-1 (HIF-1) signaling pathway. This study may provide reference for MSC based therapy of cartilage defects.

Influence of Thymectomy, Splenectomy, and Cortisone on Carcinogenesis

Groups of outbred albino CTM mice were either thymectomized or splenectomized at 4 weeks of age and administered urethan 0.4 percent in the drinking water for 10 days at 5 weeks. In comparison with intact, urethan-treated animals, the thymectomized, urethan-treated mice had a slightly lower incidence of malignant lymphomas (19 against 24 %), a marked decrease of mammary tumors (31 against 62%), and increased incidence of lung adenomas (84 against 48%) and of skin papillomas (10 against 1%). Thymectomized, but otherwise untreated mice developed less lymphomas and mammary tumors than intact, untreated controls. Splenectomy did not modify significantly the tumor incidence. In a second experiment, groups of CTM mice were administered either 1 mg of cortisone s. c. daily for 10 days or urethan in the drinking water for 5 days followed by 5 days of cortisone or viceversa, or urethan alone. No major differences in the tumor incidence in the various groups were observed, but for a decreased incidence of thymic lymphosarcomas in the group with cortisone after urethan. In a third experiment, CTM mice were given 2 mg urethan within the first day after birth and thymectomized or sham operated during the anesthesia caused by the urethan. Both groups had a very high incidence of hepatomas and lung adenomas, and developed only few lymphomas and mammary tumors. Finally, a group of C3H mice thymectomized at birth under Nembutal anesthesia, developed a considerably lower incidence of hepatomas and mammary tumors than sham operated animals.

Alien H-2 Antigens on a Chemically Induced Fibrosarcoma: Further Evidence in Crude Membrane and Soluble Extracts of the Tumor

Crude membranes (CM) were obtained from in vivo subcutaneous nodules of the methylcholanthrene-incuded BALB/c fibrosarcoma C-1 by forcing tumor fragments through a mechanical press and subsequent differential centrifugation. This immunogenic tumor has been previously shown to express both H-2d and extra H-2k-like antigens. Original H-2d and alien H-2k antigenic activities were present in CM C-1 as judged by the specific inhibition of the C'-dependent cytotoxicity of monospecific H-2 alloantisera on normal 51Cr-labelled lymphoid cells. Both K- and D-end private H-2d antigens (31 and 4), and H-2d public antigens 8, 29, 35 were detected in CM C-1. In addition, the alien H-2Kk.23 private specificity and the public H-2k.1, 5, and 25 were also found in CM C-1. A weak but reproducible activity attributable to the Dk private antigen 32 was also revealed in this material. A hierarchy in the expression of both H-2d and H-2k specificities was evident in CM C-1 which paralleled, although with an overall lower antigenic activity, those of two other BALB/c (H-2d) fibrosarcomas and of a C3Hf (H-2k) lymphoma, respectively. CM from normal BALB/c and C3Hf spleens, while expressing higher amounts of all the tested H-2 antigens, displayed a hierarchy of the different specificities similar to that of neoplastic tissues. Crude soluble (CS) material was obtained from CM C-1 by deoxycholate treatment and was tested in the inhibition assay for the presence of H-2d and alien H-2k antigens. Only specificities with the highest expression in CM were found in CS, i.e. H-2.4 and 29 for H-2d and H-2.25 for H-2*. Both CM and CS from C-1, but not from another control BALB/c sarcoma, were able to significantly inhibit the activity of an oligospecific serum to the Kk-coded antigens.

Urethan Carcinogenesis in Newborn, Suckling, and Adult Mice of C57BL, C3H, BC3FJ, C3Hf, and SWR Strains

Urethan was given to four inbred strains of mice and to one hybrid, either in the drinking water at 0.4 per cent for 15–20 days to 5-week old animals, or subcutaneously 3 mg once to newborns, or intraperitoneally 1 mg/g body weight, 5 times, once every second day, to 10-day old animals. The 5 treatments starting at 10 days of age induced a high percentage of rapidly developing thymic lymphosarcomas, while in the groups treated at birth or at 5 weeks, few tumors of this type were observed. The incidence of non-thymic malignant lymphomas or leukemias was not influenced by urethan, apart from a reduction of latent period. A small number of mammary adenocarcinomas occurred among the treated females of the C57BL and SWR strains but none in the control groups. In C3Hf and BC3F1 females there was a high incidence of mammary tumors when treatment was started at 5 weeks; treatment at birth or at 10 days did not modify the control incidence. On the contrary, hepatomas developed more rapidly and in higher percentage in the animals treated at birth or at 10 days. The incidence of pulmonary adenomas was increased by treatment in all strains parallel with the spontaneous occurrence. Tumors of harderian glands, skin, kidney, thyroid, adrenals and ovaries were also more frequent among treated animals.

Electron Microscopic Study of Viral Particles in the Pancreas of Normal and Leukemic Mice

An electron microscopic study of viral particles was conducted on pancreas, thymus, and bone marrow of normal and leukemic (C57BL x C3Hf) F1 (BC3) and SWR mice. The leukemic mice had developed thymic lymphosarcoma after neonatal injection of N-nitrosomethylurea or urethan. An intense proliferation of type C particles morphologically identical to the murine leukemia virus was found in the acinar cells of the exocrine pancreas of BC3 mice. The particles were predominantly located in intracytoplasmic vacuoles but they were also numerous in dilated cisternae of the rough endoplasmic reticulum and in extracellular spaces. A substantial quantitative difference of type C particles between the pancreases of leukemic and healthy mice was not observed. No viral particles were found in the pancreas of SWR mice. In the thymus and bone marrow of BC3 and SWR mice a small number of type C particles and intracisternal type A particles was found in all the experimental and control groups. The observation of a high number of type C particles in the exocrine pancreas of BC3 mice is discussed in relation to a viral etiology of chemically-induced lymphomas.

Lymphocyte Functions in the Rat Spleen at Various Times after Urethan Administration

The effect of urethan on various spleen-lymphocyte functions was studied in the rat for 45 days after administration of the carcinogen. For 3 days following the last injection of urethan, the total cell number and LPS reactivity were greatly reduced. Certain reactivities, probably T-cell dependent functions, such as responsiveness to the in vitro mitogenic effect of PHA, Con A, and primary stimulation by histocompatibility alloantigens in the one-way reaction, were selectively enriched during the first 2 days. Thereafter several dissociations of these lymphocyte functions can be observed: i.e., various intervals succeed during which one function may be enriched and other(s) diminished. It seems that the kinetics of enrichment, decay and recovery of the T-cell subsets involved in the reactions investigated follow a distinctive profile for each one of them. It is suggested, as a working hypothesis, that the unbalanced situations derived from the time-course discordance of the quantitative changes in the various lymphocyte functions may allow, or even enhance, tumor development.

The Effect of Urethan and 7,12-Dimethylbenz[a]Anthracene on Organ Cultures of Newborn and Adult Mouse Thymuses

Thymuses of newborn and adult mice were maintained as organ cultures for 20 days. A 24 hour treatment with urethan or with 7,12-dimethylbenz(a)anthracene (DMBA) induced necrosis of the peripheral zone of the cortex in both the newborn and adult cultured thymuses. In all the DMBA treated thymuses and the newborn thymuses treated with urethan, the necrosis eventually involved a large part of the organs. In the adult thymuses treated with urethan the necrosis appeared notably reduced at the end of the 20 day observation period.

Electron Microscopic Study of Viruses in Mouse Thymuses during Leukemogenesis by Urethan

A systematic search for viral particles was carried out in thymuses of C3Hf inbred mice treated with leukemogenic doses of urethan. Thymuses collected during the tumor latent period and thymic lymphosarcomas were examined. A group of 38 mice was treated, starting at 10 days of age, with 5 i.p. doses of urethan (lmg/g body weight) once every two days. This treatment induces approximately 30 per cent thymic lymphosarcomas in C3Hf mice, after an average period of 20 weeks, whereas no spontaneous thymic lymphosarcomas develop in untreated controls. Six animals with thymic lymphosarcoma were killed between 16–32 weeks of age; the others were sacrificed at 3,5,10 and 14 weeks of age when they did not have any recognizable thymic tumor either grossly or microscopically. As control, thymuses of a group of 28 untreated mice were examined. Mature and immature type C particles morphologically indistinguishable from the murine leukemogenic viruses and intracisternal A particles were observed. The immature C particles and intracisternal A particles were found in all the groups of treated and untreated mice. Intracisternal A particles were more numerous in the untreated than in the treated animals. The number of A particles in the neoplastic thymuses was far inferior than that observed in the treated animals killed before development of lymphoma. The amount of immature C particles was always much less than that of A particles. No significant difference in the number of immature C particles was observed in all experimental groups. Mature C particles were only seen in the thymus of a few treated or untreated mice, never in thymic lymphosarcomas. Within the limits of this investigation, the results presented are not consistent with the view that urethan may act by stimulating viral multiplication.

An Interposed Pad in Open-Chest Echocardiographic Porcine Scans for Mimicking Ultrasound Signal Attenuation in a Human Chest

Opening a chest in an experimental echocardiographic animal study eliminates ultrasound signal attenuation by the chest wall. We developed a scanning technique that involves the use of an attenuative pad created from a mixture of urethane and titanium dioxide. The pad was interposed within transmission gel between the transducer face and cardiac surface in open-chest scans in a porcine model. Comparative measurements of left ventricular echogenicity without and with the pad demonstrate that the pad reproducibly causes ultrasound signal attenuation that closely mimics chest attenuation in clinical transthoracic echocardiographic studies.

[Indication and limitations of meniscus replacement]

BACKGROUND

Meniscal lesions are among the most important musculoskeletal disorders and are the most common indication for knee joint arthroplasty. However, the structural integrity and function is rarely retained, and a loss of tissue results. Thus, there is a huge demand for meniscal replacement options.

CURRENT PROCEDURES

Autografts were used in the past but did not fulfill expectations. Meniscus allografts have been developed to be a viable treatment option. However, availability is limited and evidence of a long-term chondroprotective effect scarce. Artificial scaffolds made from either collagen or PCU foam are available, which aid the regeneration of meniscal tissue and are rather intended as a partial replacement with an intact peripheral rim. Those implants thus have a limited spectrum of indication. While they seem to be symptomatically effective, it remains unclear whether they can reduce secondary cartilage damage. Newer developments aim at a permanent replacement of lost meniscal tissue.

LIMITATIONS

In summary, there is currently no meniscal replacement available for a broad range of indications and with a solid scientific foundation. Prophylactic use should be limited to cases with a high chance of progression to osteoarthritis, like a lateral total meniscectomy. Otherwise meniscal replacement should be considered in younger, symptomatic patients with mild to moderate secondary changes. Potential causes of the initial meniscal injury like instability or deformities should be carefully assessed and addressed. In many cases, osteotomy might be a viable alternative to meniscus replacement.

Reduction of intradiscal pressure by the use of polycarbonate-urethane rods as compared to titanium rods in posterior thoracolumbar spinal fixation

Loss of sagittal alignment and balance in adult spinal deformity can cause severe pain, disability and progressive neurological deficit. When conservative treatment has failed, spinal fusion using rigid instrumentation is currently the salvage treatment to stop further curve progression. However, fusion surgery is associated with high revision rates due to instrumentation failure and proximal junctional failure, especially if patients also suffer from osteoporosis. To address these drawbacks, a less rigid rod construct is proposed, which is hypothesized to provide a more gradual transition of force and load distribution over spinal segments in comparison to stiff titanium rods. In this study, the effect of variation in rod stiffness on the intradiscal pressure (IDP) of fixed spinal segments during flexion-compression loading was assessed. An ex vivo multisegment (porcine) flexion-compression spine test comparing rigid titanium rods with more flexible polycarbonate-urethane (PCU) rods was used. An increase in peak IDP was found for both the titanium and PCU instrumentation groups as compared to the uninstrumented controls. The peak IDP for the spines instrumented with the PCU rods was significantly lower in comparison to the titanium instrumentation group. These results demonstrated the differences in mechanical load transfer characteristics between PCU and titanium rod constructs when subjected to flexion-compression loading. The concept of stabilization with a less rigid rod may be an alternative to fusion with rigid instrumentation, with the aim of decreasing mechanical stress on the instrumented segments and the possible benefit of a decrease in the incidence of screw pullout.

Ultrasensitive GSH-Responsive Ditelluride-Containing Poly(ether-urethane) Nanoparticles for Controlled Drug Release

A novel ultrasensitive redox-responsive system for the controlled release of doxorubicin (DOX) was fabricated by ditelluride-containing poly(ether-urethane) copolymers. In this study, the ditelluride group was introduced for the first time into water-soluble copolymers used for drug delivery. Doxorubicin loaded in the copolymer nanoparticles can be released in a controlled manner through the cleavage of ditelluride bonds by glutathione (GSH). The ditelluride-containing poly(ether-urethane) nanoparticles were demonstrated to be biocompatible as drug delivery vehicles, therefore opening a new avenue in drug delivery systems for chemotherapy. Furthermore, the in vitro and in vivo studies revealed that the DOX-loaded ditelluride-containing poly(ether-urethane) nanoparticles exhibited efficient uptake in cancer cells, specific tumor targeting and antitumor activity, indicating their excellent potential as novel nanocarriers for drug delivery and cancer therapy.

The Combination of Three Natural Compounds Effectively Prevented Lung Carcinogenesis by Optimal Wound Healing

The tumor stroma has been described as "normal wound healing gone awry". We explored whether the restoration of a wound healing-like microenvironment may facilitate tumor healing. Firstly, we screened three natural compounds (shikonin, notoginsenoside R1 and aconitine) from wound healing agents and evaluated the efficacies of wound healing microenvironment for limiting single agent-elicited carcinogenesis and two-stage carcinogenesis. The results showed that three compounds used alone could promote wound healing but had unfavorable efficacy to exert wound healing, and that the combination of three compounds made up treatment disadvantage of a single compound in wound healing and led to optimal wound healing. Although individual treatment with these agents may prevent cancer, they were not effective for the treatment of established tumors. However, combination treatment with these three compounds almost completely prevented urethane-induced lung carcinogenesis and reduced tumor burden. Different from previous studies, we found that urethane-induced lung carcinogenesis was associated with lung injury independent of pulmonary inflammation. LPS-induced pulmonary inflammation did not increase lung carcinogenesis, whereas decreased pulmonary inflammation by macrophage depletion promoted lung carcinogenesis. In addition, urethane damaged wound healing in skin excision wound model, reversed lung carcinogenic efficacy by the combination of three compounds was consistent with skin wound healing. Further, the combination of these three agents reduced the number of lung cancer stem cells (CSCs) by inducing cell differentiation, restoration of gap junction intercellular communication (GJIC) and blockade of the epithelial-to-mesenchymal transition (EMT). Our results suggest that restoration of a wound healing microenvironment represents an effective strategy for cancer prevention.

[MECHANISMS OF MODULATION OF REFLEX CONTROL OF BREATHING AT ELEVATED SYSTEMIC LEVEL OF PROINFLAMMATORY CYTOKINE INTERLEUKIN-1β]

This study explores the hypothesis about the possible involvement of the cyclooxygenase pathway in the effects of interleukin-1beta (IL-1β) on the breathing pattern and Heuring-Breuer respiratory reflexes. Respiratory frequency (fR), tidal volume (VT) and esophageal pressure were recorded in 29 adult male Wistar rats anaesthetized with urethane. Heuring-Breuer reflexes were tested by airway occlusion at achieving functional residual capacity (inspiratory-inhibitory reflex), and at the height of inspiration (expiratory-promoting reflex). It had been shown that an elevation of IL-1β in the systemic circulation causes an increase in VT, fR, lung ventilation and strengthens respiratory reflexes. These respiratory effects had not been shown if IL-1β administered after intraperitoneal injection of diclofenac, which had not any significant respiratory effects by itself. Because diclofenac is a non-specific antagonist of cyclooxygenases, it had been concluded that the prostaglandins mediate respiratory effects of IL-1β in point of fact.