Methods to achieve tissue-mimetic physicochemical properties in hydrogels for regenerative medicine and tissue engineering.

Hydrogels are water-swollen polymeric matrices with properties that are remarkably similar in function to the extracellular matrix. For example, the polymer matrix provides structural support and adhesion sites for cells in much of the same way as the fibers of the extracellular matrix. In addition, depending on the polymer used, bioactive sites on the polymer may provide signals to initiate certain cell behavior. However, despite their potential as biomaterials for tissue engineering and regenerative medicine applications, fabricating hydrogels that truly mimic the physicochemical properties of the extracellular matrix to physiologically-relevant values is a challenge. Recent efforts in the field have sought to improve the physicochemical properties of hydrogels using advanced materials science and engineering methods. In this review, we highlight some of the most promising methods, including crosslinking strategies and manufacturing approaches such as 3D bioprinting and granular hydrogels. We also provide a brief perspective on the future outlook of this field and how these methods may lead to the clinical translation of hydrogel biomaterials for tissue engineering and regenerative medicine applications.

Temperate phage-antibiotic synergy across antibiotic classes reveals new mechanism for preventing lysogeny.

A recent demonstration of synergy between a temperate phage and the antibiotic ciprofloxacin suggested a scalable approach to exploiting temperate phages in therapy, termed temperate phage-antibiotic synergy, which specifically interacted with the lysis-lysogeny decision. To determine whether this would hold true across antibiotics, we challenged Escherichia coli with the phage HK97 and a set of 13 antibiotics spanning seven classes. As expected, given the conserved induction pathway, we observed synergy with classes of drugs known to induce an SOS response: a sulfa drug, other quinolones, and mitomycin C. While some ß-lactams exhibited synergy, this appeared to be traditional phage-antibiotic synergy, with no effect on the lysis-lysogeny decision. Curiously, we observed a potent synergy with antibiotics not known to induce the SOS response: protein synthesis inhibitors gentamicin, kanamycin, tetracycline, and azithromycin. The synergy results in an eightfold reduction in the effective minimum inhibitory concentration of gentamicin, complete eradication of the bacteria, and, when administered at sub-optimal doses, drastically decreases the frequency of lysogens emerging from the combined challenge. However, lysogens exhibit no increased sensitivity to the antibiotic; synergy was maintained in the absence of RecA; and the antibiotic reduced the initial frequency of lysogeny rather than selecting against formed lysogens. Our results confirm that SOS-inducing antibiotics broadly result in temperate-phage-specific synergy, but that other antibiotics can interact with temperate phages specifically and result in synergy. This is the first report of a means of chemically blocking entry into lysogeny, providing a new means for manipulating the key lysis-lysogeny decision.IMPORTANCEThe lysis-lysogeny decision is made by most bacterial viruses (bacteriophages, phages), determining whether to kill their host or go dormant within it. With over half of the bacteria containing phages waiting to wake, this is one of the most important behaviors in all of biology. These phages are also considered unusable for therapy because of this behavior. In this paper, we show that many antibiotics bias this behavior to "wake" the dormant phages, forcing them to kill their host, but some also prevent dormancy in the first place. These will be important tools to study this critical decision point and may enable the therapeutic use of these phages.

Perceived stigma, discrimination and psychological problems among patients with epilepsy.

Objective: The current study sought to investigate the effects of perceived stigma and discrimination on epilepsy patients' psychological problems, such as depression, anxiety, and quality of life. Study design: A purposive sampling technique was used in this cross-sectional study. Materials and methods: The sample consisted of 186 patients with epilepsy. The Stigma Scale, Depression Anxiety Stress Scale, and Quality of life in Epilepsy-10 were used to measure the study variables. Results: Findings showed that both the perception of stigma and discrimination have a significant positive correlation with depression as well as anxiety. Stigma is a significant positive predictor of depression and anxiety at [F (1, 184) = 27.8, 15.92, p < 0.001, 0.001, respectively] and explains 12.7 and 7.5% variance that could be attributed to Stigma. Stigma is also a significant predictor of quality of life at [F (1, 184) = 16.10, p < 0.001] and explains the 7.5% variance that could be attributed to Stigma. Results also indicate that discrimination is a significant positive predictor of depression and anxiety at [F (1, 184) = 32.39, 19.91, p < 0.001] and explains 15 and 9.8 % variance, respectively, that could be attributed to Stigma. However, stigma negatively predicts quality of life at [F (1, 184) = 20.34, p < 0.001] and explains 10 % variance. Non-significant differences were found in all the demographic variables (i.e., gender, socio-economic status, and disease duration), except the quality of life was significantly high among individuals with high Socio-economic status. Conclusions: Stigma is significantly higher in epileptic patients and has a detrimental effect on the patient's quality of life, recovery, and prognosis. Thus, there is undoubtedly a need to address psychological issues, most notably the stigma associated with illnesses. Psychologists, psychiatrists, other physicians, and care givers of epileptic patients must pay close attention to the stigma in this patient population.

Bringing resistance modulation to epidemic methicillin resistant S. aureus of dairy through antibiotics coupled metallic oxide nanoparticles.

The current study probed methicillin resistant S. aureus from milk of different dairy farms along with its response to multiple antibiotics, assessment of risk factors, and response to antibiotic coupled nanoparticle. XRD of Np was confirmed as miller indices (hkl) values i.e. (101), (100), (002), (110), (012) and (013) while STEM finally revealed 40-60 nm nanorods in aggregated form. Total of 6 preparations viz a viz gentamicin (G), chloramphenicol (C), zinc oxide nanoparticle (Np), gentamicin coupled Np (GNp), chloramphenicol coupled Np (CNp), and simultaneously coupling of gentamicin and chloramphenicol on Np (GCNp) were formulated for their potential to bring resistance modulation. Data analysis of this study revealed 24.59% MRSA from dairy milk appearing potentially associated (OR> 1, p < 0.05) with most of assumed risk factors. MRSA in response to various antibiotics showed highest resistance against amoxicillin (100%), penicillin (100%), vancomycin (100%), and linezolid (90%). Zone of inhibitions were increased by 249.76% (GNp), 184.86% (CNp), and 279.76% (GCNp) in case of coupled preparations. Significant reduced minimum inhibitory concentration was observed in case of GCNp (7.8125 ± 0.00 µg/mL) followed by GNp (15.00 ± 0.00 µg/mL) and CNp (41.67 ± 18.042 µg/mL) as compared to Np alone (125.00 ± 0.00 µg/mL). Minimum bactericidal concentrations for GCNp, GNp, and CNp, and Np were 31.125, 62.5, 125, and 500 µg/mL, respectively. The study thus concluded increased prevalence of MRSA while coupling of ZnO nanoparticles with antibiotics significantly brought resistance modulation to MRSA.

Temperate phage-antibiotic synergy eradicates bacteria through depletion of lysogens.

There is renewed interest in bacterial viruses (phages) as alternatives to antibiotics. All phage treatments to date have used virulent phages rather than temperate ones, as these can integrate into the genome of the bacterial host and lie dormant. However, temperate phages are abundant and easier to isolate. To make use of these entities, we leverage stressors known to awaken these dormant, integrated phages. Co-administration of the temperate phage HK97 with sub-inhibitory concentrations of the antibiotic ciprofloxacin results in bacterial eradication (≥8 log reduction) in vitro. This synergy is mechanistically distinct from phage-antibiotic-synergy described for virulent phages. Instead, the antibiotic specifically selects against bacteria in which the phage has integrated. As the interaction between temperate phages and stressors such as ciprofloxacin are known to be widespread, this approach may be broadly applicable and enable the use of temperate phages to combat bacterial infections.