vitamin-k-semiquinone-radical and Bone-Demineralization--Pathologic

The purpose of this paper was to review the literature concerning the treatment of chronic kidney disease-mineral bone disorder (CKD-MBD) in the elderly peritoneal dialysis (PD) patient.. Chronic kidney disease-mineral bone disorder is a major problem in the elderly PD patient, with its associated increased fracture risk, vascular calcification, and accelerated mortality fracture risk. Peritoneal dialysis, however, bears a lower risk than hemodialysis (HD). The approach to CKD-MBD prophylaxis and treatment in the elderly PD patient is similar to other CKD patients, with some important differences. Avoidance of hypercalcemia, hyperphosphatemia, and hyperparathyroidism is important, as in other CKD groups, and is generally easier to attain. Calcium-free phosphate binders are recommended for normocalcemic and hypercalcemic patients. Normalization of vitamin D levels to > 75 nmol/L (> 30 pg/L) and low-dose active vitamin D therapy is recommended for all patients. Hyperparathryoidism is to be avoided by using active vitamin D and cinacalcet. Particular attention should be paid to treating protein malnutrition. Fracture prophylaxis (exercise, use of walkers, dwelling modifications) are important. Hypomagnesemia is common in PD and can be treated with magnesium supplements. Vitamin K deficiency is also common and has been identified as a cause of vascular calcification. Accordingly, warfarin treatment for this age group is problematic.. While treatment principles are similar to other dialysis patient groups, physicians should be aware of the special problems of the elderly group.

Topics: Aged; Aged, 80 and over; Bone Demineralization, Pathologic; Bone Density; Bone Diseases, Metabolic; Calcium; Dietary Supplements; Exercise; Female; Follow-Up Studies; Fractures, Spontaneous; Geriatric Assessment; Humans; Magnesium; Male; Peritoneal Dialysis; Renal Insufficiency, Chronic; Risk Assessment; Treatment Outcome; Vitamin D; Vitamin K

The effect of vitamin K2 (menaquinone-7) on bone metabolism in the femoral-metaphyseal tissues of normal and skeletal-unloaded rats was investigated. Skeletal unloading was designed using a model of hindlimb suspension; the rats were fed for the 4 days of unloading. The metaphyseal tissues obtained from normal and skeletal-unloaded rats were cultured for 48 h in medium containing either vehicle or vitamin K2 (10(-6) and 10(-5) M). The presence of vitamin K2 (10(-5) M) caused a significant increase in alkaline phosphatase activity and calcium content in the metaphyseal tissues from normal rats. Such an effect was not seen in the bone tissues from skeletal-unloaded rats. Additionally, the presence of zinc sulfate (10(-5) M) in effective concentration produced a significant increase in alkaline phosphatase activity and calcium content in the metaphyseal tissues from normal and skeletal-unloaded rats. In the presence of vitamin K2 (10(-5) M), the stimulatory effect of zinc sulfate on bone calcium content was appreciably enhanced; although this effect was completely abolished by cycloheximide (10(-6) M), an inhibitor of protein synthesis. This study demonstrates that the effect of vitamin K2 (menaquinone-7) on trabecular bone calcification in rats with skeletal unloading-induced osteopenia is enhanced by zinc in vitro. The enhancement with zinc may be based on a newly synthesized protein in the bone tissues.

Topics: Alkaline Phosphatase; Animals; Bone Demineralization, Pathologic; Calcium; Cells, Cultured; Cycloheximide; DNA; Drug Interactions; Female; Femur; Immobilization; Protein Synthesis Inhibitors; Rats; Rats, Wistar; Vitamin K; Vitamin K 2; Weight-Bearing; Zinc

The role of vitamin K in microgravity related bone loss is explored. Previous research has suggested a role for vitamin K in increasing bone formation and decreasing bone resorption in postmenapausal women. This paper describes an experiment performed during the EUROMIR-95 spaceflight involving vitamin K supplements. Experimental design and methods are discussed, along with the rationale for conducting the experiment. No results are given.

Topics: Administration, Oral; Aerospace Medicine; Bone Demineralization, Pathologic; Bone Density; Bone Remodeling; Bone Resorption; Humans; Space Flight; Vitamin K; Weightlessness; Weightlessness Countermeasures