Graphene oxide based crosslinker for simultaneous enhancement of mechanical toughness and self-healing capability of conventional hydrogels

Extraordinary self-healing efficiency is rarely observed in mechanically strong hydrogels, which often limits the applications of hydrogels in biomedical engineering. We have presented an approach to utilize a special type of graphene oxide-based crosslinker (GOBC) for the simultaneous improvement of toughness and self-healing properties of conventional hydrogels. The GOBC has been prepared from graphene oxide (GO) by surface oxidation and further introduction of vinyl groups. It has been designed in such a way that the crosslinker is able to form both covalent bonds and noncovalent interactions with the polymer chains of hydrogels. To demonstrate the efficacy of GOBC, it was incorporated in a conventional polyacrylamide (PAM) and polyacrylic acid (PAA) hydrogel matrix, and the mechanical and self-healing properties of the prepared hydrogels were investigated. In PAM-GOBC hydrogels, it has been observed that the mechanical properties such as tensile strength, Young''s modulus, and toughness are significantly improved by the incorporation of GOBC without compromising the self-healing efficiency. The PAM-GOBC hydrogel with a modulus of about 0.446 MPa exhibited about 70% stress healing efficiency after 40 h. Whereas, under the same conditions a PAM hydrogel with commonly used crosslinker N,N′-methylene-bis(acrylamide) of approximately the same modulus demonstrated no self-healing at all. Similar improvement of self-healing properties and toughness in PAA-GOBC hydrogel has also been observed which demonstrated the universality of the crosslinker. This crosslinker-based approach to improve the self-healing properties is expected to offer the possibility of the application of commonly used hydrogels in many different sectors, particularly in developing artificial tissues.

Introduction of a two-dimensional graphene oxide-based crosslinker simultaneously improve the mechanical and self-healing properties of hydrogels by offering an interesting combination of covalent and reversible hydrogen bonds to polymer backbones.     

Management of Adnexal Torsion in the Pediatric and Adolescent Population at Western Australia's Single Tertiary Children's Hospital over the Last 10 Years: Retrospective Study

ObjectiveTo review our institutional data regarding the management of adnexal torsion (AT) and assess the ovarian conservation rates.DesignRetrospective study.SettingTertiary children's hospital.PatientsPediatric and adolescent patients with surgically diagnosed AT. Participants (n = 54, mean age 9.80 ± 3.95 years) were identified between June 2010 and May 2019.InterventionsSurgical management of AT.Measurements and Main ResultsThe primary outcome was to determine the ovarian conservation rates in AT cases. The secondary outcomes were to determine the incidence of AT to total emergency department (ED) presentations, decision to operation theater (OT) time in AT cases, return to OT, histopathology, and follow-up with ultrasound to determine ovarian function. Data were collected on demographic and clinical characteristics. Continuous data were compared with t tests or Kruskal-Wallis tests; categoric data were compared with chi-square tests. A total of 52 (96.29%) patients had ovarian conservation, and 53 (98.14%) had laparoscopic management.The incidence rate for AT cases to total ED presentations for the last 10 years was 9.9 per 100 000, which was based on a Poisson distribution. Presentations to an ED for AT cases have trended upward since 2010.Decision to OT time was statistically significantly shorter in cases with preoperative suspicion of AT than those with intraoperative diagnosis of AT (p = .000). A total of 7 (12.96%) patients returned to OT for suspicion of recurrent torsion. Of these, 5 (9.26%) had confirmed repeat AT.The presence of fever, pain duration, severity of pain, and severity of torsion did not correlate with the follow-up ultrasound findings of ovarian activity.ConclusionThe findings from our study suggest that high ovarian conservation rates are achievable in AT cases. A high index of suspicion is required to prevent a delay in surgery.     

An unusual case of Plasmodium vivax malaria monoinfection associated with crescentic glomerulonephritis: a need for vigilance

Plasmodium vivax infection is increasingly a major public health burden and the second most frequent human malaria. Higher levels of clinical severity and chloroquine resistance are major factors responsible for such increases. Malarial glomerular injury is uncommon and mainly observed in Plasmodium malariae-infected patients. Occasionally, transient immune complex-mediated glomerulonephritis is associated with Plasmodium falciparum infection. Coexistent crescentic glomerulonephritis and vivax malaria have not previously been reported. We report a fatal case of P. vivax malaria, who presented with acute renal failure. P. vivax monoinfection status was diagnosed with peripheral blood smear and rapid antigen test. Further evaluation for renal failure related to systemic illness and immunological markers were inconclusive. He was treated with antimalarial drugs, hemodialysis, and supportive therapy. Renal biopsy performed for nonrecovering renal failure reveled crescentic glomerulonephritis. This case highlights the need to thoroughly search for malaria-associated crescentic glomerulonephritis using renal biopsy after nonrecovering renal failure.     

Predictors of placebo group decline in the Alzheimer's disease Assessment Scale-cognitive subscale (ADAS-Cog) in 24 week clinical trials of Alzheimer's disease

One limitation of several recent 24 week Alzheimer's disease (AD) clinical trials was the lack of cognitive decline detected by the AD Assessment Scale-cognitive subscale (ADAS-cog) in the placebo groups, possibly obscuring true medication effects. Data from 733 individuals in the placebo arms of six AD clinical trials performed 1996-1997 were pooled to examine the relationship of clinical, demographic, and genetic characteristics with the 24 week change in ADAS-cog. Baseline cognitive and functional status and the screening-to-baseline change in ADAS-cog were the strongest independent predictors of the 24 week change in ADAS-cog. The ADAS-cog did not detect progression in patients with mild dementia (screening Mini-Mental State Exam, MMSE, >or=20). The change in ADAS-cog from screening to baseline was inversely correlated with the 24 week change score; it was more difficult to detect cognitive decline at 24 weeks if individuals markedly worsened from screening to baseline. The effects of baseline MMSE and screening-to-baseline change in ADAS-cog generalized to the placebo group (N=106) of another AD study performed in 2004-2005. Overcoming lack of placebo decline in AD clinical trials will require scales more sensitive to cognitive decline in mild AD and strategies to reduce within-person variability in outcome measures.     

GTR with three different types of membranes in the treatment of intrabony periodontal defects: three-year results in sixty consecutive cases

The aim of the present study was to evaluate the clinical results at 3 years following treating intrabony periodontal defects with different nonresorbable and bioabsorbable membrane barriers. Sixty intrabony periodontal defects were treated according to the principles of guided tissue regeneration (GTR). Twenty pockets were treated with Gore Resolut, a bioabsorbable membrane; 20 were treated with Gore-Tex, a titanium-reinforced membrane; and 20 with nonresorbable Gore-Tex membrane (all manufactured by Gore Regenerative Technologies, Flagstaff, AZ). The therapeutic results were evaluated by assessing probing pocket depth (PPD), recession of the gingival margin (GR), and clinical attachment level (CAL) at baseline, at 1 and at 3 years after therapy. The postoperative phase was uneventful in all cases. At 1 year after surgery, the results showed a mean PPD reduction from 9.42 mm to 3.35 mm (p < 0.0001) with Resolut; from 10.30 mm to 4.00 with titanium-reinforced Gore-Tex (p < 0.0001); and from 8.40 mm to 3.73 mm (p < 0.0001) with Gore-Tex membranes. The mean GR increased from 1.92 mm to 3.70 mm (p < 0.001) with Resolut; from 0.47 mm to 2.85 mm (p < 0.0001) with titanium-reinforced Gore-Tex; and from 0.73 mm to 2.15 mm (p < 0.0001) with Gore-Tex membranes. The mean CAL changed from 11.35 mm to 6.92 mm (p < 0.001) with Resolut; from 10.78 mm to 6.85 mm (p < 0.0001) with titanium-reinforced Gore-Tex; and from 9.13 mm to 5.87 mm (p < 0.0001) with Gore-Tex membranes. The clinical results at 3 years were not significantly different when compared with the 1-year results (p > 0.05). No significant differences existed between the mean changes in PPD, GR, and CAL in the three different test groups. Furthermore, one tooth scheduled for extraction for periodontal and prosthodontic reasons was treated with Resolut. Histological analysis 6 months after treatment demonstrated the neoformation of a connective tissue attachment and of new alveolar bone. This additional evidence thus proved that treatment with bioabsorbable membranes according to GTR principles delivers not only clinical improvement, but also histological periodontal regeneration.