Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0235394 (wasting)
 8,040 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Abnormalities of the inorganic phosphate (Pi) reabsorption in the kidney result in various metabolic disorders. Na+-dependent Pi (Na/Pi) transporters in the brush border membrane of proximal tubular cells mediate the rate-limiting step in the overall Pi-reabsorptive process. Type IIa and type IIc Na/Pi cotransporters are expressed in the apical membrane of proximal tubular cells and mediate Na/Pi cotransport; the extent of Pi reabsorption in the proximal tubules is determined largely by the abundance of the type IIa Na/Pi cotransporter. However, several studies suggest that the type IIc cotransporter in Pi reabsorption may also play a role in this process. For example, mutation of the type IIc Na/Pi cotransporter gene results in hereditary hypophosphatemic rickets with hypercalciuria, suggesting that the type IIc transporter plays an important role in renal Pi reabsorption in humans and may be a key determinant of the plasma Pi concentration. The type IIc Na/Pi transporter is regulated by parathyroid hormone, dietary Pi, and fibroblast growth factor 23, and studies suggest a differential regulation of the IIa and IIc transporters. Indeed, differences in temporal and/or spatial expression of the type IIa and type IIc Na/Pi transporters may be required for normal phosphate homeostasis and bone development. This review will briefly summarize the regulation of renal Pi transporters in various Pi-wasting disorders and highlight the role of a relatively new member of the Na/Pi cotransporter family: the type IIc Na/Pi transporter/SLC34A3.
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PMID:New aspect of renal phosphate reabsorption: the type IIc sodium-dependent phosphate transporter. 1768 85

The importance of fibroblast growth factor 23 (FGF-23) in the pathogenesis of phosphate wasting disorders has been established, but controversy remains about how parathyroid hormone (PTH), which also stimulates urinary phosphate excretion, regulates the circulating level of FGF-23. We found that the serum FGF-23 concentration was higher in PTH-cyclin D1 transgenic mice, a model of primary hyperparathyroidism, than in wild-type mice. The serum FGF-23 concentration was significantly and directly correlated with serum PTH and calcium, and inversely correlated with phosphate levels in 90- to 118-week-old mice (all P < 0.005). Quantitative real-time reverse-transcriptase PCR revealed abundant expression of fgf23 in bone, especially in calvaria. The fgf23 expression in calvaria was significantly higher in the transgenic mice compared to the wild-type mice, and correlated well with serum FGF-23 levels. There was a direct correlation between the expression of fgf23 and the expression of osteocalcin and ALP, suggesting that activation of osteoblasts is important in the regulation of FGF-23. Serum FGF-23 levels decreased in the transgenic mice after parathyroidectomy. In conclusion, PTH plays a major role in the regulation of serum FGF-23 level in primary hyperparathyroidism, likely via activation of osteoblasts in bone.
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PMID:Parathyroid hormone regulates fibroblast growth factor-23 in a mouse model of primary hyperparathyroidism. 1785 36

The clinical syndrome congestive heart failure (CHF) has its origins rooted in a salt-avid state mediated largely by effector hormones of the renin-angiotensin-aldosterone system (RAAS). In addition, a systemic illness accompanies chronic RAAS activation. Its features include: the presence of oxidative stress in diverse tissues coupled with a reduction in activity of endogenous oxidoreductases, such as Cu/Zn-superoxide dismutase and Se-glutathione peroxidase; a proinflammatory phenotype with activated immune cells and increased circulating levels of proinflammatory cytokines; and a catabolic state with loss of soft tissues and bone that eventuates in a wasting syndrome termed cardiac cachexia. Pathogenic mechanisms and pathophysiologic expressions of this illness are under active investigation. In this context and less well appreciated is the importance of a dyshomeostasis of various minerals, including Ca2+, Mg2+, Zn, and Se, and their impact on the systemic and progressive nature of CHF. A convergence of multiple factors, some hormonal (e.g., aldosteronism, secondary hyperparathyroidism, hypovitaminosis D), others pharmacologic (e.g., loop diuretics, angiotensin-converting enzyme inhibitors), predispose to the heightened excretion of these minerals in urine and feces while parathyroid hormone promotes intracellular Ca2+ overloading in diverse tissues. The importance of these macro- and micronutrients to the appearance of oxidative stress, compromised antioxidant defenses, an immunostimulatory state and tissue wasting needs to be critically addressed. So, too, must the potential for nutriceuticals, complementary to today's pharmaceuticals, to assist in the overall management of CHF.
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PMID:The importance of lost minerals in heart failure. 1797 92

Estrogen treatment causes significant hypophosphatemia in patients. To determine the mechanisms responsible for this effect, we injected ovariectomized rats with either 17beta-estradiol or vehicle for three days. Significant renal phosphate wasting and hypophosphatemia occurred in estrogen-treated rats despite a decrease in their food intake. The mRNA and protein levels of the renal proximal tubule sodium phosphate cotransporter (NaPi-IIa) were significantly decreased in estradiol-treated ad-libitum or pair-fed groups. Estrogen did not affect NaPi-III or NaPi-IIc expression. In ovariectomized and parathyroidectomized rats, 17beta-estradiol caused a significant decrease in NaPi-IIa mRNA and protein expression compared to vehicle. Estrogen receptor alpha isoform blocker significantly blunted the anorexic effect of 17beta-estradiol but did not affect the downregulation of NaPi-IIa. Our studies show that renal phosphate wasting and hypophosphatemia induced by estrogen are secondary to downregulation of NaPi-IIa in the proximal tubule. These effects are independent of food intake or parathyroid hormone levels and likely not mediated through the activation of estrogen receptor alpha subtype.
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PMID:Estrogen downregulates the proximal tubule type IIa sodium phosphate cotransporter causing phosphate wasting and hypophosphatemia. 1830 65

Congestive heart failure (CHF) is a clinical syndrome that features a failing heart together with signs and symptoms arising from renal retention of salt and water, mediated by attendant neurohormonal activation, and which prominently includes the renin-angiotensin-aldosterone system. More than this cardiorenal perspective, CHF is accompanied by a systemic illness whose features include an altered redox state in diverse tissues and blood, an immunostimulatory state with proinflammatory cytokines and activated lymphocytes and monocytes, and a wasting of tissues that includes muscle and bone. Based on experimental studies of aldosteronism and clinical findings in patients with CHF, there is an emerging body of evidence that secondary hyperparathyroidism is a covariant of CHF. The aldosteronism of CHF predisposes patients to secondary hyperparathyroidism because of a chronic increase in Ca(2+) and Mg(2+) losses in urine and feces, with a fall in their serum ionized levels and consequent secretion of parathyroid hormone. Secondary hyperparathyroidism accounts for bone resorption and contributes to a fall in bone strength that can lead to nontraumatic fractures. The long-term use of a loop diuretic with its attendant urinary wasting of Ca(2+) and Mg(2+) further predisposes patients to secondary hyperparathyroidism and attendant bone loss. Aberrations in minerals and micronutrient homeostasis that includes Ca(2+), Mg(2+), vitamin D, zinc and selenium appear to be an integral component of pathophysiologic expressions of CHF that contributes to its systemic and progressive nature. This broader perspective of CHF, which focuses on the importance of secondary hyperparathyroidism and minerals and micronutrients, raises the prospect that dietary supplements could prove remedial in combination with the current standard of care.
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PMID:Congestive heart failure is a systemic illness: a role for minerals and micronutrients. 1836 9

The stress and inflammatory responses to burn injury are associated with bone loss. The stress response entails production of large amounts of endogenous glucocorticoids that decrease osteoblasts on the mineralization surface of bone and decreases differentiation of marrow stromal cells into osteoblasts, thereby decreasing the amount of bone formation. Deficiency of osteoblasts also blocks osteoclastogenesis thus leading to low bone turnover and bone loss. The inflammatory response generates cytokines such as interleukin 1-beta and interleukin-6, which normally increase osteoclastogenic bone resorption via stimulation of osteoblast production of RANK ligand. However, in the absence of osteoblasts as a target we postulate that they attack the parathyroid gland chief cells and up-regulate the calcium-sensing receptor. The consequence of this upregulation is the lowering of the circulating calcium necessary to suppress parathyroid hormone production and the development of hypocalcemia and urinary calcium wasting. It is the parathyroid hormone suppression that causes us to postulate acute deficiency of 1,25-dihydroxyvitamin D and the consequence of this for post-burn metabolism could include derepression of the gene that controls renin production, leading to elevated levels of angiotensin II, which can contribute to insulin resistance, as can vitamin D deficiency itself. Moreover, the skin from burned patients cannot synthesize vitamin D normally. Thus vitamin D supplementation is the only means by which to ensure vitamin D sufficiency for burn victims. The proper requirement for vitamin D in acutely burned patients remains unknown.
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PMID:The interaction between burn injury and vitamin D metabolism and consequences for the patient. 1878 7

The kidney plays a crucial role in the maintenance of the body calcium (Ca(2+)) balance. Ca(2+) is an essential ion in all organisms and participates in a large variety of structural and functional processes. In mammals, active tubular Ca(2+) reabsorption is restricted to the distal part of the nephron, i.e., the late distal convoluted (DCT2) and the connecting tubules (CNT), where approximately 10-15% of the total Ca(2+) is reabsorbed. This active transcellular transport is hallmarked by the transient receptor potential vanilloid 5 (TRPV5) epithelial Ca(2+) channel, regulated by an array of events, and mediated by hormones, including 1,25-dihydroxyvitamin D(3), parathyroid hormone, and estrogen. Novel molecular mechanisms have been identified, such as the direct regulatory effects of klotho and tissue kallikrein on the abundance of TRPV5 at the apical membrane. The newly discovered mechanisms could provide potential pharmacological targets in the therapy of renal Ca(2+) wasting. This review discusses the three basic molecular steps of active Ca(2+) reabsorption in the DCT/CNT segments of the nephron, including apical entry, cytoplasmic transport, and basolateral extrusion of Ca(2+). In addition, an overview of the recently identified mechanisms governing this active Ca(2+) transport through the DCT2/CNT epithelial cells will be presented.
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PMID:Active Ca(2+) reabsorption in the connecting tubule. 1898 97

An understanding of the pathophysiologic mechanisms of post-renal transplant (PRT) bone disease is of important clinical significance. Although bone disease occurs after all solid organ transplantation, the cumulative skeletal fracture rate remains high in PRT subjects while reaching a plateau with other transplantations. One major difference in the pathophysiology of PRT bone disease is, perhaps, due to persistent renal phosphorus (Pi) wasting. Novel phosphaturic agents have recently been suggested to participate in the development of bone disease in PRT subjects. However, it is unclear as of yet whether these factors alone or in conjunction with excess parathyroid hormone (PTH) secretion play a key role in the development of negative Pi balance and consequent bone disease in this population. In this review, I present a natural history of PRT hypophosphatemia and persistent renal Pi leak, provide pathophysiologic insight into these developments, and discuss the difficulty in diagnosing these phenotypes in both adult and pediatric populations.
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PMID:Post-renal transplantation hypophosphatemia. 1960 88

There are a number of hypophosphatemic disorders due to renal phosphate wasting that cannot be explained by elevated levels of parathyroid hormone. The circulating factors responsible for the phosphaturia have been designated as phosphatonins. Studies of patients with tumor-induced osteomalacia and other genetic diseases of phosphate metabolism have resulted in the identification of a number of hormones that regulate phosphate homeostasis, including matrix extracellular phosphoglycoprotein (MEPE), secreted frizzled-related protein 4 (sFRP-4), dentin matrix protein 1 (DMP1), fibroblast growth factor 7 (FGF7), fibroblast growth factor 23 (FGF23), and Klotho. Our understanding of the actions of these hypophosphatemic peptides has been enhanced by studies in mice either overexpressing or not expressing these hormones. This review focuses on FGF23 since its regulation is disordered in diseases that affect children, such as X-linked hypophosphatemia, autosomal dominant and recessive hypophosphatemic rickets as well as chronic kidney disease. Recent studies have shown that FGF23 is unique among the FGFs in its requirement for Klotho for receptor activation. Here, we also discuss new potentially clinically important data pointing to the receptor(s) that mediate the binding and action of FGF23 and Klotho.
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PMID:Regulation of phosphate transport by fibroblast growth factor 23 (FGF23): implications for disorders of phosphate metabolism. 1966 98

Autosomal recessive hypophosphatemic rickets (ARHR) is an extremely rare disorder of autosomal recessive inheritance, characterized by hypophosphatemia resulting from renal phosphate wasting. Dentin matrix protein 1 (DMP1), a noncollagenous extracellular protein, plays critical roles in bone mineralization and phosphate homeostasis. Recently, loss-of-function mutations in DMP1 gene have been identified as the molecular cause of ARHR. Here, we describe a Japanese family that includes two ARHR-affected siblings carrying a novel mutation of the DMP1 gene. The patients were a 53-year-old woman and a 50-year-old man with short stature and skeletal deformities who were the offspring of a first-cousin marriage. Biochemical examination revealed hypophosphatemia with renal phosphate excretion and low levels of 1,25(OH)(2)D. Serum calcium, parathyroid hormone, and urinary calcium excretion were within the normal range, leading to clinical diagnosis of ARHR. Sequence analysis of peripheral leukocytes from the patients revealed that they carried a novel homozygous nonsense mutation in the DMP1 gene (98G>A, W33X), which leads to a truncated DMP protein with no putative biological function. Unaffected family members were heterozygous for the mutation. This is the first report of a Japanese family with ARHR carrying a novel mutation of the DMP1 gene.
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PMID:A novel nonsense mutation in the DMP1 gene in a Japanese family with autosomal recessive hypophosphatemic rickets. 2021 38


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