Investigation of shielding material properties for effective space radiation protection

Geant4 Monte Carlo simulations were carried out to investigate the possible shielding materials of aluminum, polyethylene, hydrides, complex hydrides and composite materials for radiation protection in spacecraft by considering two physical parameters, stopping power and fragmentation cross section. The dose reduction with shielding materials was investigated for Fe ions with energies of 500 MeV/n, 1 GeV/n and 2 GeV/n which are around the peak of the GCR energy spectrum. Fe ions easily stop in materials such as polyethylene and hydrides as opposed to materials such as aluminum and complex hydrides including high Z metals with contain little or no hydrogen. Attenuation of the primary particles in the shielding and fragmentation into more lightly charged and therefore more penetrating secondary particles are competing factors: attenuation acts to reduce the dose behind shielding while fragmentation increases it. Among hydrogenous materials, ⁶Li¹⁰BH₄ was one of the more effective shielding materials as a function of mass providing a 20% greater dose reduction compared to polyethylene. Composite materials such as carbon fiber reinforced plastic and SiC composite plastic offer 1.9 times the dose reduction compared to aluminum as well as high mechanical strength. Composite materials have been found to be promising for spacecraft shielding, where both mass and volume are constrained.

P6524The comparison of radial artery occlusion rate after distal radial artery puncture between hemodialysis and non-hemodialysis patients

Background

In recent years it has been attempted to use a distal radial artery (DRA) as a puncture site for cardiac catheterization and intervention. A patency of radial artery is important in hemodialysis patients because the radial artery is source as an arteriovenous shunt. However, the incidence of radial artery occlusion (RAO) is not known after DRA puncture.

Purpose

To compare RAO rates after DRA puncture between dialysis and non-dialysis patients.

Method

This was retrospective, observational and single center study. All consecutive 1,533 patients undergoing DRA puncture were analyzed. The primary endpoint is RAO rates. The secondary endpoint is composite bleeding adverse event rates. These endpoints were evaluated by a vascular echocardiography several hours or the next day after the procedure.

Result

Among 1,533 patients, 26 were dialysis patients and 1,504 were non-dialysis patients. 1,386 people (90.5%) succeeded in puncture. Radial artery occlusion occurred in 7 patients (0.4%), all of whom were non-dialysis patients. There was no significant difference of RAO rate in dialysis patients and non-dialysis patients.

Conclusion

When performing DRA puncture, the probability of radial artery occlusion is not higher in dialysis patients than non-dialysis patients. The DRA puncture may be one of the option as puncture site even in dialysis patients.

Effects of heat-treated Lactobacillus crispatus KT-11 strain consumption on improvement of oral cavity environment: a randomised double-blind clinical trial

Heat-treated lactic acid bacteria is added to some foods because it is easier to store and transport, and have less interference with other food ingredient compared with living lactic acid bacteria. We have reported that oral administration of heat-treated Lactobacillus crispatus KT-11 strain (KT-11) suppressed the symptoms of periodontal disease in mice orally infected with Porphyromonas gingivalis. However, the preventive effect of KT-11 on periodontal disease in human is unclear. The aim of this randomised double-blind clinical trial was to examine the effects of KT-11 consumption on the oral environment in healthy volunteers. Sixteen healthy volunteers were randomly assigned to two groups (KT-11 or placebo), and they consumed a KT-11 food tablet (1.2×1010 KT-11 cells) or a placebo food tablet (without KT-11) every day for 4 weeks. Clinical parameters including numbers of major periodontopathic bacteria in saliva, plaque score, gum conditions, and oral mucosal fluid level were evaluated at weeks 0 and 4. Amount of change in P. gingivalis numbers decreased in the KT-11 group compared to that in the placebo group at week 4. Female participants in the KT-11 group had decreased plaque scores, reddish tinge, and gingival swelling scores compared to those in the placebo group at week 4. Furthermore, male participants in the KT-11 group demonstrated increased oral mucosa fluid scores. These clinical findings suggest that daily KT-11 intake can prevent periodontal disease through the improvement of oral conditions.

A novel dual ex vivo lung perfusion technique improves immediate outcomes in an experimental model of lung transplantation

The lungs are dually perfused by the pulmonary artery and the bronchial arteries. This study aimed to test the feasibility of dual-perfusion techniques with the bronchial artery circulation and pulmonary artery circulation synchronously perfused using ex vivo lung perfusion (EVLP) and evaluate the effects of dual-perfusion on posttransplant lung graft function. Using rat heart-lung blocks, we developed a dual-perfusion EVLP circuit (dual-EVLP), and compared cellular metabolism, expression of inflammatory mediators, and posttransplant graft function in lung allografts maintained with dual-EVLP, standard-EVLP, or cold static preservation. The microvasculature in lung grafts after transplant was objectively evaluated using microcomputed tomography angiography. Lung grafts subjected to dual-EVLP exhibited significantly better lung graft function with reduced proinflammatory profiles and more mitochondrial biogenesis, leading to better posttransplant function and compliance, as compared with standard-EVLP or static cold preservation. Interestingly, lung grafts maintained on dual-EVLP exhibited remarkably increased microvasculature and perfusion as compared with lungs maintained on standard-EVLP. Our results suggest that lung grafts can be perfused and preserved using dual-perfusion EVLP techniques that contribute to better graft function by reducing proinflammatory profiles and activating mitochondrial respiration. Dual-EVLP also yields better posttransplant graft function through increased microvasculature and better perfusion of the lung grafts after transplantation.