|
| ||
|
|
||
Calcium Metabolism (calcium + metabolism)
Selected AbstractscDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucataFEBS JOURNAL, Issue 19 2005Shuo Li Calcium metabolism in oysters is a very complicated and highly controlled physiological and biochemical process. However, the regulation of calcium metabolism in oyster is poorly understood. Our previous study showed that calmodulin (CaM) seemed to play a regulatory role in the process of oyster calcium metabolism. In this study, a full-length cDNA encoding a novel calmodulin-like protein (CaLP) with a long C-terminal sequence was identified from pearl oyster Pinctada fucata, expressed in Escherichia coli and characterized in vitro. The oyster CaLP mRNA was expressed in all tissues tested, with the highest levels in the mantle that is a key organ involved in calcium secretion. In situ hybridization analysis reveals that CaLP mRNA is expressed strongly in the outer and inner epithelial cells of the inner fold, the outer epithelial cells of the middle fold, and the dorsal region of the mantle. The oyster CaLP protein, with four putative Ca2+ -binding domains, is highly heat-stable and has a potentially high affinity for calcium. CaLP also displays typical Ca2+ -dependent electrophoretic shift, Ca2+ -binding activity and significant Ca2+ -induced conformational changes. Ca2+ -dependent affinity chromatography analysis demonstrated that oyster CaLP was able to interact with some different target proteins from those of oyster CaM in the mantle and the gill. In summary, our results have demonstrated that the oyster CaLP is a novel member of the CaM superfamily, and suggest that the oyster CaLP protein might play a different role from CaM in the regulation of oyster calcium metabolism. [source] The role of 25-Hydroxyvitamin D in normal and disturbed calcium metabolismEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2003H. Reichel No abstract is available for this article. [source] 1,,25-Dihydroxyvitamin D3 modulates the murine antibody response to pneumococcal capsular polysaccharide serotype 3 through IL-12EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2005Axel Jeurissen Abstract 1,,25-Dihydroxyvitamin D3 [1,,25(OH)2D3] is a steroid hormone that regulates calcium metabolism. Besides, 1,,25(OH)2D3 also has pronounced immunomodulatory effects: it strongly inhibits dendritic cell (DC) maturation and impairs IL-12 production. We studied the effect of 1,,25(OH)2D3 on the antibody response to pneumococcal capsular polysaccharide (caps-PS) serotype 3. 1,,25(OH)2D3 inhibited the IgG2a antibody response to caps-PS serotype 3. Besides, 1,,25(OH)2D3 also inhibited IL-12 production and maturation of DC. Anti-IL-12 and exogenous IL-12, respectively, inhibited and stimulated the IgG2a antibody response to caps-PS serotype 3. Exogenous IL-12 abrogated the effect of 1,,25(OH)2D3 on the IgG2a antibody response to caps-PS serotype 3, indicating that the effect of 1,,25(OH)2D3 on the IgG2a antibody response to caps-PS serotype 3 was mediated through IL-12. In conclusion, we demonstrate that 1,,25(OH)2D3 has an inhibitory effect on the IgG2a antibody response to caps-PS serotype 3, and that this effect was mediated trough IL-12. [source] cDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucataFEBS JOURNAL, Issue 19 2005Shuo Li Calcium metabolism in oysters is a very complicated and highly controlled physiological and biochemical process. However, the regulation of calcium metabolism in oyster is poorly understood. Our previous study showed that calmodulin (CaM) seemed to play a regulatory role in the process of oyster calcium metabolism. In this study, a full-length cDNA encoding a novel calmodulin-like protein (CaLP) with a long C-terminal sequence was identified from pearl oyster Pinctada fucata, expressed in Escherichia coli and characterized in vitro. The oyster CaLP mRNA was expressed in all tissues tested, with the highest levels in the mantle that is a key organ involved in calcium secretion. In situ hybridization analysis reveals that CaLP mRNA is expressed strongly in the outer and inner epithelial cells of the inner fold, the outer epithelial cells of the middle fold, and the dorsal region of the mantle. The oyster CaLP protein, with four putative Ca2+ -binding domains, is highly heat-stable and has a potentially high affinity for calcium. CaLP also displays typical Ca2+ -dependent electrophoretic shift, Ca2+ -binding activity and significant Ca2+ -induced conformational changes. Ca2+ -dependent affinity chromatography analysis demonstrated that oyster CaLP was able to interact with some different target proteins from those of oyster CaM in the mantle and the gill. In summary, our results have demonstrated that the oyster CaLP is a novel member of the CaM superfamily, and suggest that the oyster CaLP protein might play a different role from CaM in the regulation of oyster calcium metabolism. [source] Analysis of bone mineral density in urolithiasis patientsINTERNATIONAL JOURNAL OF UROLOGY, Issue 4 2005HIDENORI TSUJI Abstract Background:, The association between hypercalciuria and bone mineral density (BMD) has been already recognized. The aim of the present study is to relate BMD to age and sex and to evaluate the calcium metabolism and hypercalciuria-defined dietary or non-dietary category in patients with urolithiasis. Methods:, The BMI of the L2,L4 lumbar vertebrae was measured in 310 renal stone patients (191 men and 119 women). Percent age matched score (%AMS), which is the percent ratio of measured BMD to the mean BMD of age-matched control subjects, was utilized for the appraisal of BMD. Low BMD groups were defined by lower than 90% of %AMS. Results:, Low BMD was observed in 27.7% of urinary stone patients, which was not a significant difference to that of control subjects (23.5%) who were measured in the health examination. In male patients with urolithiasis, the frequency of patients in whom BMD had been apt to decrease since youth was high, but there was not a proven significant difference among the three age groups (20,39 years old, 40,59 years old and 60 years old or older). In contrast, for female stone patients, the frequency of low BMD markedly increased in patients aged 40 years or older, when menopause occurs. Furthermore, in female stone patients with hypercalciuria, the frequency of reduced BMD reached more than 40%. When the cause was non-dietary hypercalciuria (classified mainly on the daily amount of urinary calcium excretion after ingestion of calculus test diet), the frequency of reduced BMD reached 65% (P < 0.01). Conclusions:, In case female stone patients with non-dietary hypercalciuria become menopausal, not only the risk of recurrent lithiasis increases, but the possibility of developing osteopenia in the future also increases. Appropriate treatments for prophylactic effects on urolithiasis or osteopenia should be considered, as judged from BMD, diet, sex, urinary calcium excretion and other factors synthetically. [source] Increasing Dietary Protein Requirements in Elderly People for Optimal Muscle and Bone HealthJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 6 2009Erin Gaffney-Stomberg MS Osteoporosis and sarcopenia are degenerative diseases frequently associated with aging. The loss of bone and muscle results in significant morbidity, so preventing or attenuating osteoporosis and sarcopenia is an important public health goal. Dietary protein is crucial for development of bone and muscle, and recent evidence suggests that increasing dietary protein above the current Recommended Dietary Allowance (RDA) may help maintain bone and muscle mass in older individuals. Several epidemiological and clinical studies point to a salutary effect of protein intakes above the current RDA (0.8 g/kg per day) for adults aged 19 and older. There is evidence that the anabolic response of muscle to dietary protein is attenuated in elderly people, and as a result, the amount of protein needed to achieve anabolism is greater. Dietary protein also increases circulating insulin-like growth factor, which has anabolic effects on muscle and bone. Furthermore, increasing dietary protein increases calcium absorption, which could be anabolic for bone. Available evidence supports a beneficial effect of short-term protein intakes up to 1.6 to 1.8 g/kg per day, although long-term studies are needed to show safety and efficacy. Future studies should employ functional measures indicative of protein adequacy, as well as measures of muscle protein synthesis and maintenance of muscle and bone tissue, to determine the optimal level of dietary protein. Given the available data, increasing the RDA for older individuals to 1.0 to 1.2 g/kg per day would maintain normal calcium metabolism and nitrogen balance without affecting renal function and may represent a compromise while longer-term protein supplement trials are pending. J Am Geriatr Soc 57:1073,1079, 2009. [source] Effect of Hormone Replacement Therapy on Bone Quality in Early Postmenopausal WomenJOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2003Ep Paschalis PhD Abstract HRT is an effective prophylaxis against postmenopausal bone loss. Infrared imaging of paired iliac crest biopsies obtained at baseline and after 2 years of HRT therapy demonstrate an effect on the mineral crystallinity and collagen cross-links that may affect bone quality. Several studies have demonstrated that hormonal replacement therapy (HRT) is an effective prophylaxis against postmenopausal bone loss, although the underlying mechanisms are still debated. Infrared spectroscopy has been used previously for analyzing bone mineral crystallinity and three-dimensional structures of collagen and other proteins. In the present study, the technique of Fourier transform infrared microscopic imaging (FTIRI) was used to investigate the effect of estrogen on bone quality (arbitrarily defined as mineral/matrix ratio, mineral crystallinity/maturity, and relative ratio of collagen cross-links [pyridinoline/deH-DHLNL]) at the ultrastructural level, in mineralized, thin tissue sections from double (before and after administration of HRT regimen; cyclic estrogen and progestogen [norethisterone acetate]) iliac crest biopsy specimens from 10 healthy, early postmenopausal women who were not on any medication with known influence on calcium metabolism. FTIRI allows the analysis of undemineralized thin tissue sections (each image analyzes a 400 × 400 ,m2 area with a spatial resolution of ,6.3 mm). For each bone quality variable considered, the after-treatment data exhibited an increase in the mean value, signifying definite changes in bone properties at the molecular level after HRT treatment. Furthermore, these findings are consistent with suppressed osteoclastic activity. [source] Parathyroid Hormone-Related Protein Induced Coupled Increases in Bone Formation and Resorption Markers for 7 Years in a Patient With Malignant Islet Cell Tumors,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2002Ph.D., Yasuhiro Takeuchi M.D. Abstract Parathyroid hormone-related protein (PTHrP) and PTH share the common PTH/PTHrP receptor. Although an elevated level of circulating PTHrP in patients with malignancies causes hypercalcemia as does PTH, chronic and systemic effects of PTHrP on bone metabolism in humans are not well understood because tumor-burden patients showing hypercalcemia usually have a poor prognosis. We investigated bone and calcium metabolism in a patient with malignant islet cell tumors showing hypercalcemia due to the elevated plasma PTHrP level for 7 years. Hypercalcemia and hypercalciuria continued throughout the clinical course in spite of frequent infusions of bisphosphonates. Bone resorption markers and a bone formation marker were consistently elevated as seen in primary hyperparathyroidism, a disease caused by an autonomous hypersecretion of PTH. Based on biochemical measurements including bone markers and serum 1,25-dihydroxyvitamin D, the clinical features of this case essentially are the same as those of primary hyperparathyroidism except for the elevated level of plasma PTHrP with suppressed intact PTH level. Therefore, it is suggested that chronic and systemic effects of PTHrP on bone as well as calcium metabolism are indistinguishable from those of PTH in human. [source] How does acantholysis occur in pemphigus vulgaris: a critical reviewJOURNAL OF CUTANEOUS PATHOLOGY, Issue 6 2006Alessandro Lanza Background:, Pemphigus vulgaris is a life-threatening autoimmune blistering disease targeting skin and mucous membranes, characterized by disruption of keratinocytes' adhesion termed acantholysis. Today multiple classes of targets are considered to play a role in the genesis of the acantholysis; of these, the classical pemphigus antigens, desmosomal cadherins (desmoglein 1 and 3) are the best characterized and considered as the most important. Additional antigens include the novel epithelial acetylcholine receptors (,9 and pemphaxin). Thus, acantholysis in pemphigus seems to result from a cooperative action of antibodies to different keratinocyte self-antigens, but the mechanisms by which epithelial cleft occurs are not yet clearly understood. In fact, the binding of the autoantibodies to these targets generates a plethora of biological effects due, on one hand, to their direct interference with adhesive function and, on the other, to more complex events involving intracellular pathways that modify proteases activity or calcium metabolism, leading to loss of cell,cell adhesion. [source] Hyperparathyroidism in dogs with hyperadrenocorticismJOURNAL OF SMALL ANIMAL PRACTICE, Issue 11 2005I. K. Ramsey Objectives: To assess the effect of canine hyperadrenocorticism (HAC) on parathyroid hormone (PTH), phosphate and calcium concentrations. Methods: PTH concentrations and routine biochemical parameters were measured in 68 dogs with HAC. Ionised calcium was measured in 28 of these dogs. The results obtained were compared with an age- and weight-matched group of 20 hospital patients that did not show signs of HAC. Results: There were significant differences between the PTH, phosphate, alkaline phosphatase, creatinine and albumin concentrations between the two groups. Total and ionised calcium concentrations were not significantly different. Most of the dogs (92 per cent) with HAC had PTH concentrations that were greater than the reference range (10 to 60 pg/ml), and in 23 dogs they were greater than 180 pg/ml. There were significant positive correlations between the PTH and basal cortisol, post-adrenocorticotropic hormone (ACTH) cortisol and alkaline phosphatase concentrations, and also the phosphate and post-ACTH cortisol concentrations. Clinical Significance: Adrenal secondary hyperparathyroidism is a cause of increased PTH concentrations and may be associated with abnormalities in calcium and phosphate metabolism in dogs with HAC. The findings of this study could explain why canine HAC may cause clinical signs such as calcinosis cutis that are associated with altered calcium metabolism. [source] Ergocalciferol promotes in vivo differentiation of keratinocytes and reduces photodamage caused by ultraviolet irradiation in hairless micePHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2004Hiroaki Mitani Background: Ergocalciferol (VD2) is usually administered orally and it is metabolized to produce its biologically active metabolites in the liver and kidney. Active vitamin D is a well-known potent regulator of cell growth and differentiation. Purpose: Active vitamin D such as 1,25-dihydroxyvitamin D3 (1,,25(OH)2D3) prevents photodamage, including wrinkles and morphologic alterations. However, its clinical and cosmetic use is limited because of its potent, associated effect on calcium metabolism. We examined the efficacy of vitamin D analogues with few adverse effects for preventing skin photodamage. Method: Topical application of VD2 to hairless mouse dorsal skin, and exposure to solar-simulating ultraviolet (UV) radiation at a dose of 10.8 J/cm2 (UVA) were performed for 15 weeks, five times a week on weekdays. At the end of the final irradiation, histological and analytical studies were performed. Results: Topical application of VD2 significantly prevented wrinkle formation and abnormal accumulation of extracellular matrix components. In addition, VD2 suppressed excessive secretion of IL-6 induced by UV irradiation in cultured human normal keratinocytes, in a dose-dependent manner. Conclusion: VD2 promoted keratinocytes differentiation in the epidermis and showed diverse physiological effects, the same as the active form of VD3. The results suggested that the suppression of skin photodamage involved the promotion of keratinocytes differentiation and suppression of IL-6 secretion induced by exposure to UV. Topical application of VD2 may become an effective means to suppress solar UV-induced human skin damage. [source] Neandertal cold adaptation: Physiological and energetic factorsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2002A. Theodore Steegmann Jr. European Neandertals employed a complex set of physiological cold defenses, homologous to those seen in contemporary humans and nonhuman primates. While Neandertal morphological patterns, such as foreshortened extremities and low relative surface-area, may have explained some of the variance in cold resistance, it is suggested the adaptive package was strongly dependent on a rich array of physiological defenses. A summary of the environmental cold conditions in which the Neandertals lived is presented, and a comparative ethnographic model from Tierra del Fuego is used. Muscle and subcutaneous fat are excellent "passive" insulators. Neandertals were quite muscular, but it is unlikely that they could maintain enough superficial body fat to offer much cold protection. A major, high-energy metabolic adaptation facilitated by modest amounts of highly thermogenic brown adipose tissue (BAT) is proposed. In addition, Neandertals would have been protected by general mammalian cold defenses based on systemic vasoconstriction and intensified by acclimatization, aerobic fitness, and localized cold-induced vasodilation. However, these defenses are energetically expensive. Based on contemporary data from circumpolar peoples, it is estimated that Neandertals required 3,360 to 4,480 kcal per day to support strenuous winter foraging and cold resistance costs. Several specific genetic cold adaptations are also proposed,heat shock protein (actually, stress shock protein), an ACP*1 locus somatic growth factor, and a specialized calcium metabolism not as yet understood. Am. J. Hum. Biol. 14:566,583, 2002. © 2002 Wiley-Liss, Inc. [source] Segmental Differences of Impaired Diastolic Relaxation Following Cardiopulmonary Bypass Surgery in Children: A Tissue Doppler StudyARTIFICIAL ORGANS, Issue 11 2009Linda B. Pauliks Abstract Impaired myocardial relaxation is an important aftereffect of cardiopulmonary bypass (CPB). Infants with their immature calcium metabolism may be particularly vulnerable. However, it has been difficult to quantitate diastolic dysfunction clinically. This study used tissue Doppler to measure regional diastolic myocardial velocities in 31 pediatric patients undergoing open heart surgery. Color tissue Doppler images were acquired in the operating room before and 8 and 24 h post CPB surgery. Early (E) and atrial (A) diastolic velocities were determined. Long axis motion was assessed from apical views near the mitral and tricuspid rings and radial wall motion from the parasternal view. The study included 31 children aged 3.6 ± 4.4 years (6 days to 16 years), with a mean weight of 14.7 ± 13.7 kg and body surface area of 0.59 ± 0.35 m2. Tissue Doppler analysis of regional wall motion revealed abnormal left ventricle (LV) and right ventricle (RV) diastolic relaxation in the early postoperative phase after CPB. Initially, all segments were significantly altered, but by 24 h, regional differences became apparent: LV radial wall motion was recovered, while longitudinal fibers in LV and RV appeared to be less resilient. RV myocardial mechanics were most abnormal. Tissue Doppler analysis may deepen our understanding of myocardial recovery and offers a sensitive tool to compare different cardioprotective strategies. [source] Topical PTH (1,34) is a novel, safe and effective treatment for psoriasis: a randomized self-controlled trial and an open trialBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2003M.F. Holick Summary Background There continues to be a need to develop new pharmacological approaches for treating the common skin disease psoriasis. Human skin produces parathyroid hormone related peptide. This peptide is a potent inhibitor of epidermal cell growth. Objectives A programme was initiated to determine whether an agonist of this peptide's receptor, PTH (1,34), could be developed as a drug to treat psoriasis. Methods PTH (1,34) was formulated in Novasome A® cream. Fifteen adult patients with chronic plaque psoriasis who had failed to respond to at least one standard treatment were enrolled in a randomized double-blinded placebo self-controlled trial. The patients topically applied to a 25-cm2 psoriatic lesion 0·1 g of either Novasome A® cream or Novasome A® cream that contained 20 ,g of PTH (1,34) twice a day for 2 months. At the end of the double-blind study, patients were enrolled in an open large area study. Ten patients applied PTH (1,34) (50 ,g per 0·1 g) once daily to their psoriatic lesions. The patients were evaluated for their global improvement and calcium metabolism. Results Novasome A® cream enhanced the percutaneous absorption of PTH (1,34) in human skin in comparison with formulations in propylene glycol or normal saline. Psoriatic lesions treated with PTH (1,34) showed marked improvement in scaling, erythema and induration. There was a 67·3% improvement in the global severity score for the lesion treated with PTH (1,34) compared with the placebo-treated lesion, which only showed a 17·8% improvement. Ten patients topically applied PTH (1,34) on all of their lesions in a stepwise manner. A Psoriasis Area and Severity Index score analysis of all the patients revealed improvement of 42·6% (P < 0·02). None of the patients experienced hypercalcaemia or hypercalciuria or developed any side-effect to the medication. Conclusions Patients who were resistant to at least one standard therapy for psoriasis had a remarkable improvement in their psoriasis when they applied PTH (1,34) to their lesion(s). No untoward toxicity was observed in any of the subjects. This pilot study suggests that topical PTH (1,34) is a safe and effective novel therapy for psoriasis. [source] Vitamin D and Cardiovascular PreventionCARDIOVASCULAR THERAPEUTICS, Issue 4 2010M. Adnan Nadir Vitamin D has been known to medical science for almost a century. Yet, it is only in the last 15 years that we have realized that the biological effects of vitamin D extend far beyond the control of calcium metabolism. Recent observational evidence suggests strong links between low vitamin D levels and a range of cardiovascular conditions, including stroke, myocardial infarction, hypertension, and diabetes. Interventional studies are beginning to explore whether vitamin D supplementation can modify vascular health and prevent cardiovascular disease. This article reviews the physiology and function of vitamin D, examines the current observational and intervention data in cardiovascular disease, and discusses future research and current practice recommendations. [source] | ||||||||||