Temperature- and strain-dependent transient microstructure and rheological responses of endblock-associated triblock gels of different block lengths in a midblock selective solvent.

Endblock associative ABA gels in midblock selective solvents are attractive due to their easily tunable mechanical properties. Here, we present the effects of A- and B-block lengths on the rheological properties and microstructure of ABA gels by considering three low and one high polymer concentrations. The triblock polymer considered is poly(methyl methacrylate)-poly(n-butyl acrylate)-poly(methyl methacrylate) [PMMA-PnBA-PMMA] and the midblock solvent is 2-ethyl-1-hexanol. The gelation temperature has been found to be strongly dependent on the B-block (PnBA) length, as longer B-blocks facilitate network formation resulting in higher gelation temperature even with lower polymer chain density. Longer A-blocks (PMMA chains) make the endblock association stronger and significantly increase the relaxation time of gels. Temperature-dependent microstructure evolution for the gels with high polymer concentration reveals that the gel microstructure does not change significantly after the gel formation takes place. The dynamic change of microstructure in an applied strain cycle was captured using RheoSAXS experiments. The microstructure orients with the applied strain and the process is reversible in nature, indicating no significant A-block pullout. Our results provide new understandings regarding the temperature and strain-dependent microstructural change of ABA gels in midblock selective solvents.

Understanding Early Hemophilic Arthropathy in Children and Adolescents Through MRI T2 Mapping.

BACKGROUND: Persons with hemophilia experience hemarthrosis, which can lead to cartilage degeneration, causing physical impairment. MRI T2 mapping has the potential to be used as a tool to evaluate early arthropathic changes and cartilage degeneration in patients with hemophilia. PURPOSE: To assess the value of MRI-T2 mapping as a tool for investigating the cartilage status of children and adolescents with hemophilic arthropathy. STUDY TYPE: Prospective, cross-sectional. SUBJECTS: Twenty-eight boys with hemophilia (aged 5-17 years) and 23 healthy boys (aged 7-17 years). FIELD STRENGTH/SEQUENCES: A multiecho spin-echo T2 -weighted gradient echo sequence was used on a 3.0T magnet. ASSESSMENT: MRI-T2 maps of ankle (tibia-talus) (n = 19) or knee (femur-tibia) (n = 9) cartilage were assessed in hemophilia and healthy groups. An anatomically-based MRI score was also assigned to each ankle/knee. STATISTICAL TESTS: Pearson's correlation coefficient (r), linear regression, intraclass correlation coefficient (ICC), and analysis of variance (ANOVA) test. RESULTS: Negative associations between age and ankle/knee cartilage T2 relaxation times were found in hemophilia (r = -0.72 [P = 0.03] to -0.55 [P = 0.01]) and healthy (r = -0.84 [P < 0.001] to -0.55 [P = 0.20]) groups. There were nonsignificant associations between ankle cartilage T2 relaxation times and MRI scores (r = -0.15 [P = 0.54] to 0.31 [P = 0.19]). DATA CONCLUSION: Results of this clinical investigation emphasize the potential importance of MRI-T2 maps as a tool to understand the functional status of cartilage in children and adolescents with hemophilic arthropathy, while holding promise for the detection of early cartilage degeneration prior to macroscopic characterization by conventional MRI. MRI-T2 mapping may provide novel information that is not reflected in the anatomically-based MRI scoring system. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2.

A high frequency of PALB2 mutations in Jamaican patients with breast cancer.

PURPOSE: Jamaica is an island nation with one of the highest breast cancer incidence rates in the Caribbean (40/100,000 per year). The contribution of cancer susceptibility gene mutations to the burden of breast cancer in Jamaica has not yet been explored. We sought to determine the prevalence of germline mutations in BRCA1, BRCA2, and PALB2 in 179 unselected Jamaican women with breast cancer. METHODS: We sequenced the entire coding regions of BRCA1, BRCA2, and PALB2 for all the study subjects. RESULTS: Overall, 8 of 179 patients (4.5%) had a mutation in one of the three genes: one in BRCA1, two in BRCA2, and five in PALB2. CONCLUSIONS: These data suggest that in addition to BRCA1 and BRCA2, PALB2 should be included in genetic testing for breast cancer patients in Jamaica.

A Survey of BRCA1, BRCA2, and PALB2 mutations in women with breast cancer in Trinidad and Tobago.

The mortality rate from breast cancer in the nation of Trinidad and Tobago is among the highest of any country in the Caribbean region. The contribution of inherited gene mutations to the burden of breast cancer in Trinidad and Tobago has not been studied. We examined the prevalence of mutations in three susceptibility genes (BRCA1, BRCA2, and PALB2) in breast cancer patients in Trinidad and Tobago. We studied 268 unselected breast cancer patients from Trinidad and Tobago and looked for mutations across the entire coding sequences of BRCA1, BRCA2, and PALB2. Overall, 28 of 268 patients (10.4 %) had a mutation in one of the three genes, including 15 in BRCA1, ten in BRCA2, two in PALB2, and one in both BRCA2 and PALB2. There were 25 different mutations identified; of these, four mutations were seen in two patients each. Given the high prevalence of mutations, it is reasonable to offer genetic testing for these three genes to all breast cancer patients in Trinidad and Tobago.

Defining Health Profession Regulators' Roles in the Canadian Healthcare System.

Health professions regulation today faces a myriad of challenges, due to both the perceived performance of regulatory colleges, how health systems have evolved, and even larger political and economic shifts such as the renegotiation of NAFTA. In this issue of Healthcare Papers, Wilkie and Tzountzouris (2017) describe the work of the College of Medical Laboratory Technologists of Ontario (CMLTO) to redefine professionalism in the context of these challenges. Their paper, and the comments of the responding authors in this issue highlight that there, is an overarching perception that health regulatory structures - across a range of professions - are not working as effectively as they should. Across this issue of Healthcare Papers, attention is drawn to the fact that more can be done to improve both the function and perception of professional regulatory bodies. However, each paper presents a different approach to how improvements in function and perception are possible.

Genetic Overview of Syndactyly and Polydactyly.

Syndactyly and polydactyly-respectively characterized by fused and supernumerary digits-are among the most common congenital limb malformations, with syndactyly presenting at an estimated incidence of 1 in 2,000-3,000 live births and polydactyly at a frequency of 1 in approximately 700-1,000 live births. Despite their relatively regular manifestation in the clinic, the etiologies of syndactyly and polydactyly remain poorly understood because of their phenotypic and genetic diversity. Further, even though concrete knowledge of genotypic links has been established for some variants of syndactyly and polydactyly, there appears to be no single comprehensive published summary of all syndromic and nonsyndromic syndactyly and polydactyly presentations, and there is decidedly no resource that maps all syndromic and nonsyndromic syndactylies and polydactylies to their genetic bases. This gap in the literature problematizes comprehensive carrier screening and prenatal diagnosis and complicates novel diagnostic attempts. This review thus attempts to collect all that is known about the genetic bases of syndromic and nonsyndromic syndactylies and polydactylies, as well as to highlight the dactyly manifestations for which no genetic bases are as yet known. Then, having established a summation of existing and missing knowledge, this work briefly outlines the diagnostic techniques that a genetics-reinforced understanding of syndactyly and polydactyly could inform.