Patient-reported difficulty in activities of daily living and corresponding muscle weakness in elderly patients undergoing haemodialysis.

AIM: Patients undergoing haemodialysis have reduced muscle strength and impaired activities of daily living (ADL). We examined possible relationship between difficult ADL and corresponding muscle weakness in elderly haemodialysis patients. METHODS: This was a single-centre, cross-sectional study. Patient-reported ADL difficulty was examined using a questionnaire in six ADL using upper limbs (eating, grooming and dressing) and lower limbs (bathing, toileting and locomotion). We measured six muscle strengths by dynamometers of shoulder flexion, shoulder abduction, elbow flexion, handgrip, hip abduction and knee extension. The muscle strength with the lowest Z-score was considered as the weakest muscle strength for the patient. RESULTS: The six scores of ADL difficulty were all inversely associated with the six muscle strengths in the 81 total participants of whom 71 individuals (87.7%) had any ADL difficulty. Among the six measurements of muscle strength, handgrip strength showed the highest associations with all ADL difficulties. In 25 patients who perceived that the most difficult ADL was an activity using upper limbs, the common weakest muscle strengths were the hip abduction, handgrip and elbow flexion. In 44 patients who perceived that the most difficult ADL was an activity using lower limbs, knee extension was the most prevalent weakest muscle strength. CONCLUSION: This study suggested preferential relationship between the most difficult ADL and corresponding muscle weakness in elderly haemodialysis patients. This finding may be useful in prevention and treatment.

Quantitative analysis of isolated and clustered DNA damage induced by gamma-rays, carbon ion beams, and iron ion beams.

Ionizing radiation induces multiple damaged sites (clustered damage) together with isolated lesions in DNA. Clustered damage consists of closely spaced lesions within a few helical turns of DNA and is considered to be crucial for understanding the biological consequences of ionizing radiation. In the present study, two types of DNA, supercoiled plasmid DNA and linear lambda DNA, were irradiated with gamma-rays, carbon ion beams, and iron ion beams, and the spectra and yield of isolated DNA damage and bistranded clustered DNA damage were fully analyzed. Despite using different methods for damage analysis, the experiments with plasmid and lambda DNA gave largely consistent results. The spectra of both isolated and clustered damage were essentially independent of the quality of the ionizing radiation used for irradiation. The yields of clustered damage as well as of isolated damage decreased with the different radiation beams in the order gamma> C > Fe, thus exhibiting an inverse correlation with LET [gamma (0.2 keV/microm) < C (13 keV/microm) < Fe (200 keV/microm)]. Consistent with in vitro data, the yield of chromosomal DNA DSBs decreased with increasing LET in Chinese hamster cells irradiated with carbon ion beams with different LETs, suggesting that the decrease in the yield of clustered damage with increasing LET is not peculiar to in vitro irradiation of DNA, but is common for both in vitro and in vivo irradiation. These results suggest that the adverse biological effect of the ionizing radiation is not simply accounted for by the yield of clustered DNA damage, and that the complexity of the clustered damage needs to be considered to understand the biological consequences of ionizing radiation.

Analysis of complex DNA lesions generated by heavy ion beams.

Ionizing radiation induces clustered DNA damage, which contains localized multiple lesions in duplex DNA molecules. It has been thought that due to complex nature, clustered DNA damage is refractory to repair or associated with error-prone repair and results in severe biological endpoints as compared to sparsely-distributed lesions. High linear energy transfer (LET) radiations such as heavy ion beams exert a greater relative biological effect (RBE) than low LET radiations such as X- and gamma-rays. In the present study, we analyzed the yields of clustered DNA damage produced by high and low LET radiations using in vitro and in vivo systems and examined whether the differential formation of clustered DNA damage accounts for distinct RBE values of these radiations.

Analysis of DNA damage generated by high-energy particles.

Ionizing radiation generates isolated and localized multiple (i.e., clustered) lesions in DNA, and the latter is believed to be primarily responsible for deleterious biological consequences such as cell killing and mutations. In the present study, we irradiated plasmid and lambda DNA by ionizing radiations with different linear energy transfer (LET) values, and compared the yields of isolated and clustered DNA lesions.