Removing the men who have sex with men blood donation deferral: Informing risk models using Canadian public health surveillance data

OBJECTIVE

Gay, bisexual and other men who have sex with men (gbMSM) were ineligible to donate blood in most countries since the 1980's. In Canada the deferral period has been incrementally decreased from lifetime to male-to-male sex in the last 3 months. Now a few countries have removed the deferral altogether. Risk models have been utilised to estimate the probability of an HIV positive donation being released into the blood supply and to inform incremental changes to the length of the deferral period. Here we use public health data to estimate the risk of HIV if the gbMSM deferral criteria were removed in Canada.

MATERIAL AND METHODS

We calculate the risk reduction among heterosexuals based on responses to standard risk questions routinely asked of donors. We assume gbMSM will donate at the same rate as heterosexual males. We apply the same risk reduction principle to HIV incidence and prevalence among gbMSM in the general population to evaluate the HIV risk without gbMSM time deferral. We model three scenarios where risk reduction is varied by assumptions about incidence and compliance with deferral criteria.

RESULTS

The estimates for all scenarios were not significantly different to the currently observed scenario which predicts a residual risk of 0.02 HIV positive per million donations (95% CI: 0.000006-0.09).

CONCLUSION

The models predict that removing the gbMSM deferral criteria would result in HIV residual risk similar to currently observed.

Platelet Inhibitory Drugs: An In Vivo Method of Evaluation in Patients

The measurement of platelet deposition in human thrombi is essential for the evaluation of platelet-inhibitory drugs and prosthetic materials for use in patients. The rate of 111Indiumlabelled platelet accumulation on Dacron arterial grafts was measured in 27 patients randomised to take either aspirin and dipyridamole (ASA + DPM) or placebo. Autologous platelets were labelled and re-injected seven days following surgery and the graft thrombogenidty index calculated as the daily rise in the ratio of emissions from the graft over a reference site.

The mean (± SD) thrombogenidty index in 12 patients undergoing femoro-popliteal bypass was 0.25 ± 0.09 on placebo and 0.16 ± 0.07 on ASA + DPM started pre-operatively (p Ã0.05). Post-operative ASA + DPM therapy started two days following platelet labelling in 15 patients with aorto-femoral grafts also significantly reduce thrombogenidty to 0.12 ± 0.05 compared with 0.25 ± 0.08 on placebo (p Ã0.01). In the latter patients the ratio of emissions from the graft over reference fell significantly on starting ASA + DPM, suggesting a net loss of platelets from the graft. These results indicate that the rate of in vivo platelet accumulation on Dacron grafts can be quantitated and that ASA + DPM reduced this rate in man.

Adsorption of ß2-Microglobulin on Dialysis Membranes: Comparison of Different Dialyzers and Effects of Reuse Procedures

In order to measure ß2-microglobulin adsorption on dialysis membranes, uremic plasma was passed through different dialyzers in a simulated hemodialysis circuit in which both plasma and dialysate compartments were organized as closed loops, the ultrafiltration pressure being adjusted to minimize water shifts. Under these conditions, comparison of the amounts of ß2-m in the plasma and dialysate compartments allowed us to calculate the binding of ß2-m to the membrane at different times of the procedure. Whereas cuprophane membrane (Gambro gf 180m, 1.8m2) did not bind ß2-m, AN69 (Filtral, 1.1 m2), high flux polysulfone (F60, 1.2m2) and modified polyamide (Polyflux 130, Gambro, 1.3m2) were found to adsorb 49 ± 8 mg (mean ± SEM), 17 ± 5 mg and 38 ± 4 mg of 82-m, respectively. These data were confirmed in trace labeling experiments with 125I-ß2-m. Adsorption was a saturable phenomenon occurring during the first 90 min of in vitro dialysis. After reuse with peracetic acid, the adsorption capacity of AN69 membrane was lowered to 20 ± 4 mg of ß2-m, contrasting with the unchanged adsorption after reuse with sodium hypochlorite. These data indicate that adsorption significantly contributes to ß2-m removal during hemodialysis with certain dialyzers and that reuse procedures may affect the propensity of dialysis membranes to bind 82-m.

Overhauser effects in non-conducting solids at 1.2 K

Recently, it was observed that protons in non-conducting solids doped with 1,3-bisdiphenylene-2-phenylallyl (BDPA) or its sulfonated derivative (SA-BDPA) can be polarized through Overhauser effects via resonant microwave irradiation. These effects were present under magic angle spinning conditions in magnetic fields between 5 and 18.8 T and at temperatures near 100 K. This communication reports similar effects in static samples at 6.7 T and, more importantly, at temperatures as low as 1.2 K, in a different dynamic regime than in the previous study. Our results provide new information towards understanding the mechanism of the Overhauser effect in non-conducting solids. We discuss possible origins of the fluctuations that can give rise to an Overhauser effect at such low temperatures.

Re-imagining dementia in the fourth age: the ironic fictions of Alice Munro

This paper analyses two stories by Alice Munro to explore how her fiction interrogates the prevailing social imaginary of the fourth age. Drawing on the theory of Gilleard and Higgs, I show how Munro's stories rely on irony and surreal imagery to subvert the logic that engenders and normalises the opposition between the third and fourth ages, and, by extension, the social death of people coping with later-life dementia. Ultimately, I argue that Munro's fiction does not so much reveal the Truth about the fourth age, as expose the reader's complicity in the construction of the prevailing gothic social imaginary.

The Effect of Compression on Venous Haemodynamics Assessed by Quantitative Photoplethysmography

Background:

The purpose of this study was to examine quantitatively the effect of compression stockings on venous haemodynamics at the level of the ankle.

Methods:

To obtain quantifiable results, a computer-controlled photoplethysmographic system was used to measure the displacement of local blood volume induced by exercise (exercise displacement volume, EDV) and by tilting the subject (tilt displacement volume, TDV). The test was repeated after application of class I compression stockings 20–30 mmHg). The ratio EDV/TDV is considered to represent the efficiency of the veno-muscular pump. Three groups of subjects were studied: a control group ( n = 8), patients with telangiectases ( n = 10) and a group with large varices ( n = 11).

Results:

The application of external compression had a quantifiable and beneficial effect on venous haemodynamics and was most significantly documented by an increase in veno-muscular efficiency (EDV/TDV) from 28% to 44% in the varicose vein patients. Statistically significant increases of EDV/TDV could also be identified in the telangiectatic patients and normal subjects. EDV also showed an increase with compression stockings; however, statistical significance was only reached in the varicose vein group.

Conclusion:

External compression (class 1 compression stockings) significantly improved venous haemodynamic indices, especially in patients with varicose veins. Quantitative photoplethysmography used in this study permits a fast, non-invasive and quantifiable evaluation of venous haemodynamics of the lower extremities.

Electron-scale measurements of magnetic reconnection in space

Magnetic reconnection is a fundamental physical process in plasmas whereby stored magnetic energy is converted into heat and kinetic energy of charged particles. Reconnection occurs in many astrophysical plasma environments and in laboratory plasmas. Using measurements with very high time resolution, NASA's Magnetospheric Multiscale (MMS) mission has found direct evidence for electron demagnetization and acceleration at sites along the sunward boundary of Earth's magnetosphere where the interplanetary magnetic field reconnects with the terrestrial magnetic field. We have (i) observed the conversion of magnetic energy to particle energy; (ii) measured the electric field and current, which together cause the dissipation of magnetic energy; and (iii) identified the electron population that carries the current as a result of demagnetization and acceleration within the reconnection diffusion/dissipation region.