Clinical calcium最新文献

Hematopoietic stem cells(HSCs)in the bone marrow(BM)are maintained in distinct microenvironments called niches. Technological advances in in vivo imaging have enabled dynamic analyses of BM cells. This in vivo imaging can be a key tool to elucidate the mechanisms underlying HSC maintenance in the BM through analysis of HSC motility and evaluation of the relationship between HSCs and their niche factors over time. Furthermore, application of this imaging technology to leukemia research can lead to new discoveries in leukemic stem cell maintenance and the development of novel antileukemic drugs. In this review, we summarize recent advances in dynamic analyses of HSCs and leukemic cells in the BM by intravital imaging.

Tendons and ligaments are dense fibrous connective tissues mainly composed of type I collagen, aligned in highly ordered arrays along the axis of the tendon and ligament. The enthesis is defined as the attachment site of a tendon, ligament, joint capsule, or fascia to bone. During morphogenesis, the cell population co-expressing Scleraxis(Scx)and the SRY-box containing gene 9(Sox9)contributes to the formation of fibrocartilaginous entheses. Scx regulates tendon and ligament maturation, while Sox9 is a key regulatory factor for cartilage formation. The considerable mechanical forces transmitted through the enthesis and avascular properties of the tissue make it more prone to injuries and degenerative changes. Thus, integration of tendons or ligaments with bone following surgical repair remains a clinical challenge. In this review, we summarize the current knowledge regarding the formation, maintenance, damage, and repair of fibrocartilaginous entheses, focusing on the rotator cuff tendon-to-bone attachment sites.

In Japan, school lunches are provided to elementary and secondary student, not only for ensuring the intake of well-balanced and nutritious meal, but also hoping to improve their dietary habits. In this article, the authors review the effects of a school lunch program on the bone mass and dietary habits. The school lunch program was divided into 3 groups:a group provided with a complete school lunch, a group provided with only milk supplements, and a group provided with no supplement. The calcaneal bone mass was significantly higher in both primary and the junior high-school students given complete lunches compared with that in the other groups. Moreover, the intake of milk and milk products besides school lunches was more frequent in the groups that received complete lunches. The results suggest that the school lunch program, particularly that providing complete lunches, contributed to increasing the bone mass and improving the dietary habits.

Osteoporosis is one of chief complications of anorexia nervosa. Their calcium intake decreases and 84%are lack of vitamin D. The abnormal bone metabolism in severely emaciated patients with anorexia nervosa involves both a reduction in bone formation and an increase in bone resorption. The annual change in lumbar bone mineral density(BMD)is significantly correlated with body mass index(BMI)at the entry. The critical BMI for a positive increase in BMD was 16.4±0.3 kg/m2. Since 30%of patients are lack of vitamin K, their bone quality deteriorates. The risk factors of a decrease in lumbar vertebrae BMD is a duration of emaciation when both serum levels of insulin-like growth factor-Ⅰ as a potent osteogenic factor and estradiol as a powerful bone resorption inhibitor decrease. Therefore, the prevention and the treatment are weight gain. However, the patient does not accept weight gain easily. Active form vitamin D3 of 0.5μg/day or 30-45 mg/day of vitamin K2 preparation prevents the further decrease in bone mineral density. Eldecalcitol of 0.5μg/day shows about 5%increase in lumbar vertebrae BMD in first year. Bisphosphonate and a RANK ligand inhibitors, denosumab should not be used for young patients and women in hope of the pregnancy.

Increased fracture incidence and ectopic calcifications which are accompanied with mineral metabolic disorders are well seen in dialysis patients. The role of bone in chronic kidney disease patients including dialysis has been investigated in clinical findings and experimental examinations. The abnormalities of osteocyte function have been pointed to as an active inducer of pathology of a deregulated endocrine organ.

Animal studies using mice model such as vitamin D deficiency and global and conditional VDR knock out(KO)mice have disclosed that the physiological role of vitamin D strongly depends on the calcium balance. Vitamin D stimulates active intestinal calcium transport mechanism, thereby maintains normocalcemia that has priority over skeletal integrity. Besides the biological significance of vitamin D extensively studied, its precise function in non-classical target needs further investigation.

Extracellular calcium concentrations are tightly regulated within a narrow range through the coordinated participation of the parathyroid glands, kidneys, and bone. In patients with chronic kidney disease, the production of 1,25-dihydroxyvitamin D and urinary calcium excretion decrease as kidney function declines. When patients reach end-stage renal disease and start dialysis, calcium metabolism is further complicated by loss of kidney function, calcium flux during dialysis, and pronounced impact of bone metabolism on extracellular calcium concentrations. In this article, I outline the alterations in calcium metabolism during the progression of chronic kidney disease and after initiation of dialysis, review data on the effects of secondary hyperparathyroidism and osteoporosis medications on calcium metabolism, and discuss the characteristic aspects of altered calcium homeostasis in end-stage renal disease.

The aging of society is coming up in Japan and it is one of the most important issues for us to prevent or reduce frailty and sarcopenia, two major causes of disability in older adults. In centenarians, the frailty and sarcopenia could be key factors to determine the prognosis. Maintaining both physical and cognitive functions influences the improvement of QOL and the independence of ADL. Recent studies have demonstrated pathogenic roles of age-related inflammatory activation(inflammaging), and some of circulation biomarkers for frailty are developed. It is important to prevent frailty and sarcopenia by caring a lifestyle from the earlier ages in life, preparing for the aging society with healthy status.

Many of the adverse outcomes of frailty are probably mediated by sarcopenia. Unfortunately, there are currently no approved drug treatments for sarcopenia. Osteoporosis and sarcopenia are common in older age. A study on activated vitamin D revealed that muscle mass could be maintained by administering alfacalcidol to patients with osteoporosis. Bisphosphonate therapy, which is a gold standard for osteoporosis treatment, may help to maintain muscle mass.

Previous studies demonstrated that patients undergoing chronic dialysis therapy showed several times higher risks for hip fracture compared to those of healthy subjects. Their bone tissue would be vulnerable because of the bone loss and poor quality. In addition, volume and strength of the muscle are decreased and the ratio of sarcopenia or frailty is increased among these patients, accordingly leading to higher risks for falls and bone fractures. Considering the pathophysiology of bone fracture in dialysis patients, it is a matter of course that one wonders how effective recently developed medicine for"classical" osteoporosis is. However, evidence to guide us is currently lacking. Therefore, it is crucial for us to construct evidence by observational and interventional studies.