Metabolic engineering with adaptive laboratory evolution for phenylalanine production by Corynebacterium glutamicum.

The mutants resistant to a phenylalanine analog, 4-fluorophenylalanine (4FP), were obtained for metabolic engineering of Corynebacterium glutamicum for producing aromatic amino acids synthesized through the shikimate pathway by adaptive laboratory evolution. Culture experiments of the C. glutamicum strains which carry the mutations found in the open reading frame from the 4FP-resistant mutants revealed that the mutations in the open reading frames of aroG (NCgl2098), pheA (NCgl2799) and aroP (NCgl1062) encoding 3-deoxy-d-arabino-heptulosonate-7-phosphate, prephenate dehydratase, and aromatic amino acid transporter are responsible for 4FP resistance and higher concentration of aromatic amino acids in their culture supernatants in the 4FP-resistant strains. It was expected that aroG and pheA mutations would release feedback inhibition of the enzymes involved in the shikimate pathway by phenylalanine and that aroP mutations would prevent intracellular uptake of aromatic amino acids. Therefore, we conducted metabolic engineering of the C. glutamicum wild-type strain for aromatic amino acid production and found that phenylalanine production at 6.11 ± 0.08 g L-1 was achieved by overexpressing the mutant pheA and aroG genes from the 4FP-resistant mutants and deleting aroP gene. This study demonstrates that adaptive laboratory evolution is an effective way to obtain useful mutant genes related to production of target material and to establish metabolic engineering strategies.

Cardiorespiratory consequences of attenuated fentanyl and augmented rocuronium dosing during protocolised prehospital emergency anaesthesia at a regional air ambulance service: a retrospective study.

BACKGROUND: Pre-Hospital Emergency Anaesthesia (PHEA) has undergone significant developments since its inception. However, optimal drug dosing remains a challenge for both medical and trauma patients. Many prehospital teams have adopted a drug regimen of 3 mcg/kg fentanyl, 2 mg/kg ketamine and 1 mg/kg rocuronium ('3:2:1'). At Essex and Herts Air Ambulance Trust (EHAAT) a new standard dosing regimen was introduced in August 2021: 1 mcg/kg fentanyl, 2 mg/kg ketamine and 2 mg/kg rocuronium (up to a maximum dose of 150 mg) ('1:2:2'). The aim of this study was to evaluate the cardiorespiratory consequences of a new attenuated fentanyl and augmented rocuronium dosing regimen. METHODS: A retrospective study was conducted at EHAAT as a service evaluation. Anonymized records were reviewed from an electronic database to compare the original ('3:2:1') drug dosing regimen (December 2019-July 2021) and the new ('1:2:2') dosing regimen (September 2021-May 2023). The primary outcome was the incidence of absolute hypotension within ten minutes of induction. Secondary outcomes included immediate hypertension, immediate hypoxia and first pass success (FPS) rates. RESULTS: Following exclusions (n = 121), 720 PHEA cases were analysed (360 new vs. 360 original, no statistically significant difference in demographics). There was no difference in the rate of absolute hypotension (24.4% '1:2:2' v 23.8% '3:2:1', p = 0.93). In trauma patients, there was an increased first pass success (FPS) rate with the new regimen (95.1% v 86.5%, p = 0.01) and a reduced incidence of immediate hypoxia (7.9% v 14.8%, p = 0.05). There was no increase in immediate hypertensive episodes (22.7% vs. 24.2%, p = 0.73). No safety concerns were identified. CONCLUSION: An attenuated fentanyl and augmented rocuronium dosing regimen showed no difference in absolute hypotensive episodes in a mixed cohort of medical and trauma patients. In trauma patients, the new regimen was associated with an increased FPS rate and reduced episodes of immediate hypoxia. Further research is required to understand the impact of such drug dosing in the most critically ill and injured subpopulation.

Regulating Electrostatic Interactions toward Thermoresponsive Hydrogels with Low Critical Solution Temperature.

Low critical solution temperature (LCST) of commonly used thermoresponsive polymers in water is basically dominated by hydrophobic interactions. Herein, a novel thermoresponsive system based on electrostatic interactions is reported. By simply loading aluminum chloride (AlCl3 ) into non-responsive poly(2-hydroxyethyl acrylate) (PHEA) hydrogels, PHEA-Al gels turn to have reversible thermoresponsive behavior between transparent and opaque without any volume change. Further investigations by changing metal ion-polymer compositions unravel the necessity of specific electrostatic interactions, namely, cation-dipole bonding interactions between hydroxy groups and trivalent metal ions. The thermoresponsive hydrogel demonstrates high transparency (≈95%), excellent luminous modulation capability (>98%), and cyclic reliability, suggesting great potential as an energy-saving material. Although LCST control by salt addition is widely known, salt-induced expression of thermoresponsiveness has barely been discussed before. This design provides a new approach of easy fabrication, low cost, and scalability to develop stimuli-responsive materials.

Structure and properties of gelatin edible film modified using oxidized poly(2-hydroxyethyl acrylate) with multiple aldehyde groups.

BACKGROUND: Pure gelatin film usually exhibits characteristics of being brittle and hydrophilic, which limit its wide use in food packing fields. In this study gelatin/oxidized poly(2-hydroxyethylacrylate) (G/OP) composite films were prepared using casting techniques, the aim of this research was to investigate the effects of OP on the structures and properties of the G/OP composite films. RESULTS: The Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy results indicated that the G/OP films retained their original secondary structure and random coiled conformation. However, the surface and cross-sectional morphologies of the G/OP films were rougher than those of pure gelatin films, cracks and agglomerates appeared with increasing OP dosage. The remarkable transparency of the G/OP film at 280 nm indicated excellent ultraviolet (UV) light barrier properties of the film, which inhibited UV-light-induced food oxidation. Moreover, the addition of OP decreased the water content and water solubility and considerably increased the water contact angle of pure gelatin films from 78.8° to 116.2° (a maximum increase of 37.5°). This suggested that OP modification improved the hydrophobicity of gelatin films. Furthermore, the inclusion of OP significantly promoted the flexibility of gelatin films, thereby improving their brittleness. CONCLUSIONS: The UV light barrier properties, hydrophobicity, and flexibility of gelatin films were improved via OP modification, thus the produced G/OP composite films have the potential to be used in food packaging. © 2022 Society of Chemical Industry.

Pre-hospital emergency anaesthesia in trauma patients: An observational study from a state-wide Australian pre-hospital and retrieval service.

OBJECTIVE: To assess the performance of an Australian pre-hospital and retrieval medicine (PHRM) service against the National Institute for Health and Care Excellence (NICE) standard which recommends that pre-hospital emergency anaesthesia (PHEA) in trauma patients should be conducted within 45-min of first contact with emergency services. METHODS: Retrospective observational study of all adult trauma patients in which PHEA was conducted by the PHRM service covering a 5-year period from January 2015 to December 2019. RESULTS: Over the 5-year study period, 1509 (22%) of the PHRM service workload comprised primary retrievals from scene. Most 1346 (89%) of these cases had a primary diagnosis of trauma. Of these we have complete data for 328 of the 337 cases requiring a PHEA and 121 (37%) patients received this within the recommended 45-min time frame. The service attended in rapid response vehicles (n = 160, 49%), rotary wing (n = 151, 46%) and fixed wing (n = 17, 5%) transport modalities. For a service covering 983 482 km2 , the median distance travelled to patients was 35 (16-71) km and the median time to PHEA was 54 (38-80) min. CONCLUSIONS: In a cohort of 337 patients treated by a dedicated PHRM service in South Australia, the median time to PHEA was 54 (38-80) min with only 37% of patients receiving PHEA within 45 min from the activation of the team. Despite differing patient demographics, the percentage of patients receiving PHEA within the recommended time frame was greater than a similar cohort from the UK. However, both data sets still fall short of recommended targets.

Spatial distribution of single guest molecules along thickness of thin films of poly(2-hydroxyethyl acrylate).

We have investigated three-dimensional distribution and diffusion behaviors of single guest dyes in 1-µm thick films of poly(2-hydroxyethyl acrylate) (PHEA) by using astigmatism imaging method. Perylene diimide derivative (BP-PDI) in the PHEA films localized along the Z-axis at ca. Z = 600-700 nm distant from the interface (Z = 0) between PHEA and glass substrate. This Z-localization was not observed in different polymer films of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), and polystyrene (PSt). Because the glass transition temperature of the PHEA is lower than the room temperature, BP-PDI in the PHEA films exhibited Brownian motion, normal diffusion on the XY plane and confined motion along the Z-direction. For elucidating the mechanism of the peculiar localization of the guest dyes along film thickness in the PHEA films, we measured diffusion behaviors of different dyes, R6G and Atto 488, in 1-µm thick PHEA films, obtaining result that the Z-distributions of the dyes were overall similar to that of BP-PDI. The result indicates that the Z-localization of the guest dyes should be ascribed not to the interaction between glass surface and guest dye but mainly to the Z-dependent property of the PHEA film. Indeed, the lateral diffusion coefficients of the guest dyes depended on their Z-positions.

A convergent synthetic platform for dual anticancer drugs functionalized by reduced graphene nanocomposite delivery for hepatocellular cancer.

Hepatocellular carcinoma (HCC) is widespread cancer with a high degree of morbidity and mortality in individuals worldwide and a serious concern for its resistance to present chemotherapy drugs. In this investigation, the combination of cisplatin (CPT) and metformin (MET) to kill the HepG2 and caco-2 cells was developed into a new pH-responding magnetic nanocomposite based on reduced graphene oxide. Polyhydroxyethyl methacrylic (PHEA) was then linked employing grafting from approach to the reduced graphene oxide by ATRP polymerization (Fe3O4@rGO-G-PSEA). FT-IR, SEM, XRD, DLS, and TGA analyses evaluated physicochemical characteristics of the nanocomposite. In addition, the cellular uptake property of the nanocomposites was examined by the HepG2 cells. The outcomes of cell viability results indicate that the nanoparticles loaded with MET&CPT showed the lowest concentration rate of HepG2 and Caco-2 cells compared to the drug-loaded single nanocomposite groups and free drugs. The histological analysis has demonstrated relatively safe and does not produce different stress such as swelling and inflammation of the mice organs. Our results show the enhancement in cytotoxicity in HepG2 and Cocoa-2 cells by MET and CPT graphene oxide-based nanocomposite by promoting apoptotic response. Moreover, Fe3O4@rGO-G-PSEA showed potent in vivo antitumor efficacy but showed no adverse toxicity to normal tissues. Together, this study can provide insight into how surface embellishment may tune these nanocomposites' tumor specificity and provide the basis for developing anticancer efficacy.

Smart material based on boron crosslinked polymers with potential applications in cancer radiation therapy.

Organoboron compounds have been playing an increasingly important role in analytical chemistry, material science, health applications, and particularly as functional polymers like boron carriers for cancer therapy. There are two main applications of boron isotopes in radiation cancer therapy, Boron Neutron Capture Therapy and Proton Boron Fusion Therapy. In this study, a novel and original material consisting of a three-dimensional polymer network crosslinked with [Formula: see text]B enriched boric acid molecules is proposed and synthesized. The effects of the exposition to thermal neutrons were studied analyzing changes in the mechanical properties of the proposed material. Dedicated Monte Carlo simulations, based on MCNP and FLUKA main codes, were performed to characterize interactions of the proposed material with neutrons, photons, and charged particles typically present in mixed fields in nuclear reactor irradiations. Experimental results and Monte Carlo simulations were in agreement, thus justifying further studies of this promising material.

A convenient approach by using poly-(HEMA-co-NIPAM)/Cu2+ solution sol-gel transition for wound protection and healing.

Rapid and convenient wound healing is crucial for reducing potential post-traumatic wound complications. In this study, a temperature-sensitive polymer of poly-(HEMA-co-NIPAM) (PHN) was synthesized by free-radical polymerization, in which the solution quickly underwent a sol-gel transition above 29°C, thus responding to a typical body temperature and facilitating wound sealing. PHN solution incorporated with copper ions (PHN-Cu) not only exhibited excellent antibacterial properties, but also expedited wound closure and facilitated tissue angiogenesis. The in vivo and in vitro experiments showed that the PHN-Cu had a higher wound closure rate and demonstrated an ability to promote skin tissue angiogenesis. Such a versatile, convenient aqueous solution could enable nonprofessionals to promptly treat wounds in a short time after injury, thus providing suitable conditions for later treatment, and can be used as a convenient method to clean wounds.

Microengineered poly(HEMA) hydrogels for wearable contact lens biosensing.

Microchannels in hydrogels play an essential role in enabling a smart contact lens. However, microchannels have rarely been created in commercial hydrogel contact lenses due to their sensitivity to conventional microfabrication techniques. Here, we report the fabrication of microchannels in poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogels that are used in commercial contact lenses with a three-dimensional (3D) printed mold. We investigated the corresponding capillary flow behaviors in these microchannels. We observed different capillary flow regimes in these microchannels, depending on their hydration level. In particular, we found that a peristaltic pressure could reinstate flow in a dehydrated channel, indicating that the motion of eye-blinking may help tears flow in a microchannel-containing contact lens. Colorimetric pH and electrochemical Na+ sensing capabilities were demonstrated in these microchannels. This work paves the way for the development of microengineered poly(HEMA) hydrogels for various biomedical applications such as eye-care and wearable biosensing.

Influence of Polyvinyl Alcohol (PVA) on PVA-Poly-N-hydroxyethyl-aspartamide (PVA-PHEA) Microcrystalline Solid Dispersion Films.

This study was conducted to formulate buccal films consisting of polyvinyl alcohol (PVA) and poly-N-hydroxyethyl-aspartamide (PHEA), to improve the dissolution of the drug through the oral mucosa. Ibuprofen sodium salt was used as a model drug, and the buccal film was expected to enhance its dissolution rate. Two different concentrations of PVA (5% w/v and 7.5% w/v) were used. Solvent casting was used to prepare films, where a solution consisting of drug and polymer was cast and allowed to dry. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to investigate the properties of films. In vitro dissolution studies were also conducted to investigate drug release. SEM studies showed that films containing a higher concentration of PVA had larger particles in microrange. FTIR studies confirmed the presence of the drug in films and indicated that ibuprofen sodium did not react with polymers. DSC studies confirmed the crystalline form of ibuprofen sodium when incorporated within films. In vitro dissolution studies found that the dissolution percentage of ibuprofen sodium alone was increased when incorporated within the film from 59 to 74%. This study led to the development of solid microcrystalline dispersion as a buccal film with a faster dissolution rate than the drug alone overcoming problem of poor solubility.

Diclofenac sustained release from sterilised soft contact lens materials using an optimised layer-by-layer coating.

A layer-by-layer (LbL) coating was designed using ionic polysaccharides (chitosan, sodium alginate, sodium hyaluronate) and genipin (crosslinker), to sustain the release of diclofenac sodium salt (DCF) from soft contact lens (SCL) materials. The coating was hydrophilic, biocompatible, non-toxic, reduced bacterial growth and had minor effects on the physical properties of the material, such as wettability, ionic permeability, refractive index and transmittance, which remained within the recommended values for SCLs. The coating was applied on a silicone-based hydrogel and on commercial SofLens and Purevision SCLs. The coating attenuated the initial drug burst and extended the therapeutic period for, at least, two weeks. Relevantly, the problems of sterilizing drug loaded SCLs coated with biopolymers, using classic methods that involve high temperature or radiation, were successfully solved through high hydrostatic pressure (HHP) sterilization.

Poly(N-isopropylacrylamide)-based dual-crosslinking biohybrid injectable hydrogels for vascularization.

Injectable hydrogels provide a powerful and non-invasive approach for numerous applications in cell transplantation, growth factor delivery, tissue regeneration and so forth. The properties of injectable hydrogels should be well-tuned for specific applications, where their overall design should ensure biocompatibility, non-toxicity, robust mechanical properties, and most importantly the ability to promote vascularization and integration with the host tissue/organ. Among these criteria, vascularization remains a key design element in the development of functional therapeutic hydrogels for successful translation into clinical settings. To that end, there is still a critical need for the development of the next generation of injectable hydrogels with precisely tuned biophysical and biochemical properties which could simultaneously promote tissue vascularization. In this work, we developed a temperature responsive, dual-crosslinking, biohybrid hydrogels, modified with a vasculogenic peptide for applications in regenerative medicine, specifically tissue vascularization. The synthesized hydrogels consisted of poly(N-isopropylacrylamide)-based copolymer, functionalized gelation and angiogenic VEGF-mimetic QK peptide with enhanced shear-thinning and injectability properties. QK peptide is a VEGF-mimetic vasculogenic peptide which binds to VEGF receptors and activates intercellular pathway for vascularization. Apart from the presence of QK peptide, the mechanical properties of the hydrogels were precisely tuned by altering the polymer concentration, enabling successful assembly and endothelial cell network formation. Extended in vitro studies demonstrated successful encapsulation and homogeneous distribution of endothelial cells within the three-dimensional (3D) environment of the hydrogel matrix with significantly enhanced vascularization in presence of the QK peptide as early as 3 days of culture. A small, preliminary in vivo study in mice showed a trend of increased blood vessel formation in hydrogels that incorporated the QK peptide. Overall, our study presents the design and characterization of injectable, dual-crosslinking and vasculogenic hydrogels with controlled properties which could be utilized for numerous applications in regenerative medicine, minimally invasive cell and drug delivery as well as fundamental studies on tissue vascularization and angiogenesis. STATEMENT OF SIGNIFICANCE: In this work, we synthesized a new class of temperature responsive, dual-crosslinking, biohybrid injectable hydrogels with enhanced vascularization properties for broad applications in regenerative medicine and minimally invasive cell/drug delivery. The developed hydrogels properly accommodated 3D culture, assembly and network formation of endothelial cells, as evidenced by in vitro and in vivo studies.

Clinical and radiographic features of hydrolyzed MIRAgel scleral buckles: A comparative analysis.

The MIRAgel (hydrogel) scleral buckle, introduced in the 1980s, was a novel material to repair retinal detachments. It was later discontinued due to the frequency of long-term complications related to buckle hydrolysis and expansion. These complications included pain, limited extraocular motility, and more serious complications such as infection or scleral perforation, which ultimately necessitated surgical extraction as late as 20-30 years after placement. Prompt and proper diagnosis and treatment is often delayed as these buckle-associated complications frequently mimic other orbital pathologies such as tumors or infections. The hydrolyzed MIRAgel buckle exhibits distinct radiographic features that are helpful in arriving at the correct diagnosis, particularly in cases of ambiguous clinical presentation or history. Here, we expand on the previously described radiographic features of hydrolyzed MIRAgel and compare them to features of common, mimicking orbital pathology.

Chrysin and Docetaxel Loaded Biodegradable Micelle for Combination Chemotherapy of Cancer Stem Cell.

PURPOSE: Cancer stem cells (CSCs) have been suggested to represent the main cause of tumour progression, metastasis and drug resistance. Therefore, these cells can be an appropriate target to improve cancer treatment. METHODS: A novel biodegradable brush copolymeric micelle was synthesized by the ring-opening polymerization (ROP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. The obtained micelle was used for co-delivery of the anticancer drug docetaxel (DTX) and Chrysin (CHS) as an adjuvant on the CSCs originated from Human colon adenocarcinoma cell line. Cancer stem cells were enriched by MACS technique and characterized by flow cytometry analysis against CD133 marker. RESULTS: Data demonstrated that the micelles harbouring DTX@CHS had potential to reduce cancer stem cell viability compared to free DTX@CHS, single-drug formulations and the control group (p < 0.05). The combination effect of DTX and CHS formulated in micelle was synergistic in CSCs (CI < 1). The reactive oxygen species content was shown to increase after cell treatment with DTX@CHS loaded on micelles (p < 0.05). DTX@CHS-micelles inhibited cancer stem cell migration rate in vitro (p < 0.05), indicating an impaired metastasis activity. CONCLUSION: In conclusion, the synthesized DOX@CHS-micelles can be applied in the introduction of anticancer agents to resistant cancer population by further investigations.

Optic Nerve Compression From MIRAgel Implant Migration in a Monocular Patient.

The MIRAgel implantation was popularized in the 1980s as an alternative to silicone for scleral buckle retinal detachment repair. However, long-term follow-up has revealed that the implants can expand, creating globe compression and potentially visually devastating intraocular invasion. The authors document a 33-year-old monocular male patient presenting 20 years after MIRAgel implantation with extensive expansion, posterior migration, globe compression, and possible optic nerve compression. Debulking of the MIRAgel stabilized the vision and restored affected extraocular movements. The authors highlight that posterior MIRAgel migration can cause optic nerve compression, and implant debulking may require a multi-disciplinary approach. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:815-818.].

Sulindac encapsulation and release from functional poly(HEMA) microparticles prepared in supercritical carbon dioxide.

Sulindac loaded poly(HEMA) cross-linked microparticles were synthesized via one-pot free-radical dispersion polymerisation in supercritical carbon dioxide (scCO2) in presence of photocleavable diblock stabilisers based on polyethylene oxide (PEO) and poly(heptadecafluorodecyl acrylate) (PFDA) bearing a o-nitrobenzyl photosensitive junction (hv) (PEO-hv-PFDA), and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Poly(HEMA) cross-linked microparticles either empty or sulindac loaded were obtained with well-defined spherical morphology with the sizes between 250 and 350 nm. Additionally, upon UV-photolysis the stabiliser on the surface was cleaved which permits to microparticles to be redispersed in water leading to water swollen microgels about 2.1-3.6 µm. Moreover, the release behaviour from obtained microgels indicated the sustained release of sulindac over 10 days. Besides, the surface modification after UV-photolysis was studied and proved that the particles can be functionalised with further chemistries.