Peroxidase and Senescence

ABSTRACT Kinetin and a.a'-dipyridyl prevented the rapid decrease of chlorophyll content in detached oat leaves senescing in the dark. In the light, detachment caused a 27-40% rise in peroxidase activity and kinetin enhanced the enzyme in the segments by about 80%. Darkness prevented any detachment-induced rise of the activity and decreased the stimulating action of kinetin and mechanical injury. The effect of dipyridyl on peroxidase activity in the dark was similar to that of kinetin. Kinetin enhanced the same distinctive isoperoxidases under light and dark conditions. Neither horseradish peroxidase nor that extracted from oat leaves showed any ability to hydroxylate free proline in vitro. A system which supposedly led to peroxidase-catalysed proline hydroxylation yielded small amounts of hydroxyproline in the absence of the enzyme. Staining with Fast Blue BB salt in the presence of IAA as a substrate after electrophoresis indicated that all detected oat isoperoxidases had an IAA oxidase activity visually paralleling their peroxidase activity. Crude extracts contained IAA oxidase inhibitors that could be partially or fully removed by dialysis. The possible significance of the rise in peroxidase activity during senescence is discussed

Dental Health and Mortality in People With End-Stage Kidney Disease Treated With Hemodialysis: A Multinational Cohort Study

Background Dental disease is more extensive in adults with chronic kidney disease, but whether dental health and behaviors are associated with survival in the setting of hemodialysis is unknown. Study Design Prospective multinational cohort. Setting & Participants 4,205 adults treated with long-term hemodialysis, 2010 to 2012 (Oral Diseases in Hemodialysis [ORAL-D] Study). Predictors Dental health as assessed by a standardized dental examination using World Health Organization guidelines and personal oral care, including edentulousness; decayed, missing, and filled teeth index; teeth brushing and flossing; and dental health consultation. Outcomes All-cause and cardiovascular mortality at 12 months after dental assessment. Measurements Multivariable-adjusted Cox proportional hazards regression models fitted with shared frailty to account for clustering of mortality risk within countries. Results During a mean follow-up of 22.1 months, 942 deaths occurred, including 477 cardiovascular deaths. Edentulousness (adjusted HR, 1.29; 95% CI, 1.10-1.51) and decayed, missing, or filled teeth score ≥ 14 (adjusted HR, 1.70; 95% CI, 1.33-2.17) were associated with early all-cause mortality, while dental flossing, using mouthwash, brushing teeth daily, spending at least 2 minutes on oral hygiene daily, changing a toothbrush at least every 3 months, and visiting a dentist within the past 6 months (adjusted HRs of 0.52 [95% CI, 0.32-0.85], 0.79 [95% CI, 0.64-0.97], 0.76 [95% CI, 0.58-0.99], 0.84 [95% CI, 0.71-0.99], 0.79 [95% CI, 0.65-0.95], and 0.79 [95% CI, 0.65-0.96], respectively) were associated with better survival. Results for cardiovascular mortality were similar. Limitations Convenience sample of clinics. Conclusions In adults treated with hemodialysis, poorer dental health was associated with early death, whereas preventive dental health practices were associated with longer survival