Synthesis and characterisation of fluorescent pyrene‐end‐capped polylactide fibres

Fluorescent markers are critical for tracking the position and movement of molecules both in vivo and in vitro. Conventionally, synthetic dyes are non‐covalently added to polymers for fluorescent tracking, but often diffuse away. Here we demonstrate, for the first time, a facile method for the synthesis of fluorescent poly(lactic acid) nano‐/microfibres for biomedical applications using solution spin blowing. Pyrene‐end‐capped poly(l ‐lactide) (PLLA) derivatives were synthesised using the ring‐opening polymerisation of l ‐lactide and they were characterised using spectroscopic and thermal analyses. Submicrometre‐sized fluorescent fibres were produced from these PLLA derivatives using solution blow spinning techniques generating polymer blends and core–shell fibres. Such system could be further exploited to incorporate electrically conductive carbon allotropes via the pyrene aromaticity, producing fluorescent and electrically active fibres for in vitro monitoring and electrical stimulation. © 2018 Society of Chemical Industry     

Psychological disorder and mortality in French older adults: do social relations modify the association?

The possible modifying effect of social relations on the association between depression and mortality was examined in a community-based cohort study. A total of 3,777 randomly selected persons 65 years of age and older in southwest France were followed over a 5-year period from 1988 in the Personnes Agees Quid (PAQUID). At study entry, the prevalence of elevated depressive symptomatology was 12.9% for men and 14.7% for women, and the reported relative isolation was 14.1% for men and 26.0% for women. During a total of 16,984 person-years of follow-up, 849 deaths occurred. Among participants with high levels of depressive symptomatology, the age-adjusted mortality rate ratio was 2.10 (95% confidence interval 1.7-2.7) in men and 1.76 (95% confidence interval 1.4-2.3) in women. When compared with individuals with the most connections, men and women with few social network connections were also at increased risk of mortality: age-adjusted rate ratio = 2.69 (95% confidence interval 1.9-3.8) for men and 1.56 (95% confidence interval 1.0-2.4) for women. Satisfaction with social support had a small but nonsignificant effect on mortality risk. For women, the excess risks due to depressive symptoms and few network connections are observed only in the 65- to 74-year age group, after adjusting for health and health behaviors. Social relations did not significantly modify the depression-mortality associations for either men or women, although the depression-mortality effect was reduced by 12.8% in men. The latter findings do not appear to be compatible with the buffering hypothesis, whereby we would expect social relations to decrease the depression-mortality association. Nonetheless, there are independent effects from these two factors, and older men who are depressed and not socially connected are at increased risk of dying earlier.     

Optimised multiple quantum well phase modulator

Reports pin phase modulator that has been optimised for maximum phase change relative to the contrast (ratio of transmission in the 'on' state to that in the 'off' state), within certain constraints: the maximum tolerable contrast and the maximum zero bias absorption loss were chosen to be 2 and 50%, respectively. The parameters optimised were the operating wavelength, the number of quantum wells in the active layer and the position of that layer, the operating bias, the device length and the background doping in the intrinsic region. The optimised device was measured to have a phase modulation figure of merit of 27 degrees /Vmm at the optimum bias of 6 V, giving a phase change in a 385 mu m-long device of 63 degrees at this bias. The corresponding contrast was approximately 1.4. Photocurrent measurements show that the zero bias absorption loss is also within the 50% limit.<>     

Immobilization of acrylamide-modified oligonucleotides by co-polymerization

A flexible chemistry for solid phase attachment of oligonucleotides is described. Oligonucleotides bearing 5'-terminal acrylamide modifications efficiently co-polymerize with acrylamide monomers to form thermally stable DNA-containing polyacrylamide co-polymers. Co-polymerization attachment is specific for the terminal acrylamide group. Stable probe-containing layers are easily fabricated on supports bearing exposed acrylic groups, including plastic microtiter plates and silanized glass. Attachment can be accomplished using standard polyacrylamide gel recipes and polymerization techniques. Supports having a high surface density of hybridizable oligonucleotide (approximately 200 fmol/mm2) can be produced.     

Endothelin receptor blockade prevents the rise in pulmonary vascular resistance after cardiopulmonary bypass in lambs with increased pulmonary blood flow

BACKGROUND: Children with increased pulmonary blood flow may experience morbidity as the result of increased pulmonary vascular resistance after operations in which cardiopulmonary bypass is used. Plasma levels of endothelin-1, a potent vasoactive substance implicated in pulmonary hypertension, are increased after cardiopulmonary bypass. OBJECTIVES: In a lamb model of increased pulmonary blood flow after in utero placement of an aortopulmonary shunt, we characterized the changes in pulmonary vascular resistance induced by hypothermic cardiopulmonary bypass and investigated the role of endothelin-1 and endothelin-A receptor activation in postbypass pulmonary hypertension. METHODS: In eleven 1-month-old lambs, the shunt was closed, and vascular pressures and blood flows were monitored. An infusion of a selective endothelin-A receptor blocker (PD 156707; 1.0 mg/kg/h) or drug vehicle (saline solution) was then begun 30 minutes before cardiopulmonary bypass and continued for 4 hours after bypass. The hemodynamic variables were monitored, and plasma endothelin-1 concentrations were determined before, during, and for 6 hours after cardiopulmonary bypass. RESULTS: After 90 minutes of hypothermic cardiopulmonary bypass, both pulmonary arterial pressure and pulmonary vascular resistance increased significantly in saline-treated lambs during the 6-hour study period (P <.05). In lambs pretreated with PD 156707, pulmonary arterial pressure and pulmonary vascular resistance decreased (P <. 05). After bypass, plasma endothelin-1 concentrations increased in all lambs; there was a positive correlation between postbypass pulmonary vascular resistance and plasma endothelin-1 concentrations (P <.05). CONCLUSIONS: This study suggests that endothelin-A receptor-induced pulmonary vasoconstriction mediates, in part, the rise in pulmonary vascular resistance after cardiopulmonary bypass. Endothelin-A receptor antagonists may decrease morbidity in children at risk for postbypass pulmonary hypertension. This potential therapy warrants further investigation.     

Application of dried blood spot specimens for serologic subtyping of human immunodeficiency virus type 1 in Thailand

Dried blood spot (DBS) specimens were assessed as an alternative to plasma for human immunodeficiency virus type 1 (HIV-1) serotyping by V3 loop peptide enzyme immunoassay. Nested PCR capable of distinguishing HIV-1 subtypes B and E was used as the reference standard. Ninety-two percent of DBS samples were typeable as either HIV-1 subtype B or E. Serotype results with DBS and plasma were identical for 254 of 257 specimens. A simple DBS collection method provides a convenient alternative for conducting HIV-1 serotype surveillance while retaining sensitivity and specificity.     

A discussion on the use of judgment in representing uncertainty in PRAs

This paper is a review of some aspects of current practice in the analysis of uncertainties in Probabilistic Risk Assessments (PRAs). The use of judgment in performing a PRA is unavoidable due to the complexity of the analysis and the many uncertainties which surround it. In most PRAs performed to date, uncertainties have been characterized by using the subjective theory of probability to calibrate the analyst's degree of belief in various hypotheses, and the degrees of belief from different parts of the analysis have been combined to represent an overall measure of uncertainty in the bottom line results. While this may be useful in some circumstances, it may obscure some valuable insights as discussed in this paper. Historically it has been assumed that certain probabilities in the analysis of accident progression relate to stochastic variability. An example is given where a consideration of the analysis framework leads to an indication that this may be erroneous and that it may be more appropriate to regard some probabilities as characterizing modeling uncertainty.