Systemic Calcium Metabolism Research Articles

A Mouse Model of MC903-Induced Atopic Dermatitis.

Atopic dermatitis (AD) is a chronic, relapsing, and extremely pruritic inflammatory skin disease with a particular impact on children. AD pathogenesis is not yet fully understood, and there is no curative treatment for this disease. Therefore, several genetically or chemically-induced AD mouse models have been developed. These preclinical mouse models are an indispensable research tool for studying AD pathogenesis and evaluating the efficacy of new candidate AD therapeutics. A commonly used mouse model of AD has been developed using the topical application of a low-calcemic analog of vitamin D3, MC903, to induce AD-like inflammatory phenotypes that closely resemble human AD. Moreover, this model shows a minimal effect on systemic calcium metabolism that is observed in the vitamin D3-induced AD model. Thus, an expanding number of studies use the MC903-induced AD model to interrogate AD pathobiology in vivo and to test new candidate small molecule and monoclonal antibody therapies. This protocol describes in detail functional measurements including the measurement of skin thickness, which is a surrogate marker for ear skin inflammation, as well as itch assessment, histological evaluation to assess the structural changes associated with AD skin inflammation, and preparation of single-cell suspensions from ear skin and draining lymph nodes for the assessment of inflammatory leukocyte subset infiltration in these tissues using flow cytometry. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Topical application of MC903 induces AD-like skin inflammation Support Protocol 1: Measurement of ear skin thickness Support Protocol 2: Itch assessment Support Protocol 3: Dissection of ear skin and ear draining lymph nodes Support Protocol 4: Histological evaluation and quantification Support Protocol 5: Preparation of single-cell suspension from ear skin and draining lymph nodes for the assessment of inflammatory immune cell infiltration using flow cytometry.

Images - Penile pain in the setting of end-stage renal disease: An unusual anatomic location for calciphylaxis.

In this report, we present a case of penile calciphylaxis, an extremely rare and serious condition occurring in association with dysregulation of systemic calcium metabolism in the setting of chronic renal impairment. Calciphylaxis can occur at various body sites and is associated with diffuse vascular calcifications in small and medium-sized arteries of the involved tissues. Penile calciphylaxis has a grim prognosis. Calciphylaxis is an important etiologic differential diagnosis for penile necrosis and penile pain in patient’s being treated with dialysis for end-stage kidney disease. Diagnosis of penile calciphylaxis is possible via clinical and radiological evaluations. Medical management may alleviate symptoms; however surgical interventions may be necessary, and histological studies may allow for definitive classification.

The value of calcium and high-sensitivity C-reactive protein serum levels in psoriatic patients

ObjectiveThe aim was to evaluate the level of serum calcium and the serum level of high-sensitivity C-reactive protein (hsCRP) in patients with psoriasis.BackgroundPsoriasis is a systemic chronic inflammatory disease of the skin with associated comorbidity. The most detrimental aspect of psoriasis is the concurrent physical comorbidities, such as cardiovascular disease, obesity, diabetes, metabolic syndrome, inflammatory bowel disease, and psoriatic arthritis that contribute to decreased longevity. Psoriasis is one of the skin diseases that have been found to show disturbance in systemic calcium metabolism. CRP is one of the acute-phase reactant proteins, and its blood level increases during inflammatory reactions. There is a link between the concentration of CRP and cardiovascular disease development in psoriatic patients.Patients and methodsPsoriatic patients (n = 40) and age, sex-matched, and BMI-matched healthy controls (n = 40) were enrolled. Serum levels of hsCRP were measured by enzyme-linked immunosorbent assay, and assessment of serum calcium was done using enzymatic colorimetric technique.ResultsSerum calcium (P < 0.001) and serum hsCRP (P < 0.001) showed significant differences compared with controls.ConclusionSeveral biomarkers are altered in patients with psoriasis. In particular, decrease in serum calcium and increase in serum hsCRP could be of interest for further studies. A longitudinal observation study on levels of these biomarkers in response to treatment as well as a correlation of these markers with the development of concomitant diseases in patients with moderate-to-severe psoriasis should be initiated.

The Effect of Extracellular Calcium Metabolism on Aldosterone Biosynthesis in Physiological and Pathological Status.

Primary aldosteronism (PA) was reported to frequently harbor not only cardiovascular diseases but also some metabolic disorders including secondary calcium metabolic diseases. Recently, the potential association between aldosterone producing cells and systemic calcium metabolism has been proposed. For instance, PA is frequently associated with hypercalciuria or hypocalcemia, which subsequently stimulates parathyroid hormone (PTH) secretion. This altered calcium metabolism in PA patients could frequently result in secondary osteoporosis and fracture in some patients. On the other hand, extracellular calcium itself directly acts on adrenal cortex and has been also proposed as an independent regulator of aldosterone biosynthesis in human adrenals. However, it is also true that both PTH and vitamin D pathways stimulate endocrine functions of adrenal cortical adenomas to co-secret both aldosterone and cortisol. Therefore, it has become pivotal to explore the potential crosstalk between aldosterone and systemic calcium metabolism. We herein reviewed recent advances in these fields.

Vitamin Status and Mineralized Tissue Development

The physiological control of mineralized tissue development is mediated by two processes: mineralization, such as bone formation due to osteoblast activity, and mineralized tissue destruction by osteoclast bone resorption. In this system, nutritional status, including vitamin intake, influences each regulatory processes, although definite responding mechanisms in target cells vary according to each compound. In contrast with water-soluble vitamins that constant supply is required, fat-soluble vitamins such as vitamin D and K are stored in the liver and fat tissue for long time. They are metabolized into congeneric compounds with various activities to participate in the local mineralization process in the body. During physiological or non-physiological mineralization, the local actions of vitamin D and K are regulated by nutrient factor derived from dietary supply, and influenced by systemic calcium metabolism and homeostasis.

Level of Serum Calcium in Psoriatic Patients

Various forms of skin disease like psoriasis have been found to show disturbances in systemic calcium metabolism in some cases. Calcium is the major regulator of keratinocytes differentiation. The main objective of this study was to find out the serum calcium level of patients with psoriasis in comparison with control subjects without psoriasis. The present study was a case control study from July 2015 to June 2016. Consecutive type of sampling method was followed in this study. The case group was consisting of 30 psoriatic patients and the control group was consisting of 30 non psoriatic patients attended in Skin and VD department of Dhaka Medical College Hospital (DMCH) and Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka. The mean age of the psoriatic group was 35.57±7.75 years (minimum 22 years and maximum 50 years), while it was 35.17±7.32 years (minimum 23 years and maximum 48 years) in the control group. The mean serum calcium level in psoriatic patients was 8.84±0.95 mg/dl (minimum 7.2mg/dl and maximum 10.2 mg/dl) while in controls it was 9.49±0.90 mg/dl (minimum 7.7 mg/dl and maximum 10.9 mg/dl). Statistical difference was observed between case and control participants with p-value &lt;0.05. Hypocalcemia was observed in 33.33% psoriatic patients as compared 10% in controls (P value &lt;0.05). In conclusion, serum calcium levels were lower in psoriatic patients than in control subjects. It is better to include dairy foods as calcium resource in daily diet of patients suffering from psoriasis.&#x0D; CBMJ 2016 July: Vol. 05 No. 02 P: 29-32

Involvement of Systemic Calcium Metabolism on Treatment with Oral Implants

Involvement of Systemic Calcium Metabolism on Treatment with Oral Implants

Parathyroid hormone-related protein overexpression protects goat mammary gland epithelial cells from calcium-sensing receptor activation-induced apoptosis.

Normal mammary gland epithelial cells and breast cancer cells express the calcium-sensing receptor (CaSR), which is the master regulator of systemic calcium metabolism. During lactation, activation of the CaSR in mammary epithelial cells downregulates parathyroid hormone-related protein (PTHrP) levels in milk and in the circulation, and increases calcium transport into milk. However, very little information is available on the role of CaSR in goat mammary gland epithelial cells (GMECs) apoptosis. In this investigation, the full-length cDNA of CaSR from Xinong Saanen dairy goats was cloned, which contains an open-reading frame of 3,258 bp encoding 1,085 amino acids with a predicted molecular weight of 121.0 kDa and an isoelectric point of 5.65. The amino acid sequence is highly homologous with sheep, and the goat CaSR gene is mapped to chromosome 1. Quantitative real-time PCR suggested that CaSR was predominantly expressed in the heart, kidney and mammary gland. Then, we found the stimulation of CaSR with its activator gadolinium chloride (GdCl3) contributed to increase CaSR mRNA levels in GMECs and simultaneously promoted cell apoptosis, and these effects were abrogated partially by NPS2390 which is an inhibitor of CaSR. We also demonstrated that Ca(2+) increased CaSR mRNA levels and induced GMECs apoptosis and restrained cell proliferation. In contrast, PTHrP overexpression protected GMECs from calcium-induced apoptosis, and promoted cell proliferation. In conclusion, these results suggest that PTHrP overexpression protects GMECs from CaSR activation-induced apoptosis.

Switching of G-protein Usage by the Calcium-sensing Receptor Reverses Its Effect on Parathyroid Hormone-related Protein Secretion in Normal Versus Malignant Breast Cells

The calcium-sensing receptor (CaR) is a G-protein-coupled receptor that signals in response to extracellular calcium and regulates parathyroid hormone secretion. The CaR is also expressed on normal mammary epithelial cells (MMECs), where it has been shown to inhibit secretion of parathyroid hormone-related protein (PTHrP) and participate in the regulation of calcium and bone metabolism during lactation. In contrast to normal breast cells, the CaR has been reported to stimulate PTHrP production by breast cancer cells. In this study, we confirmed that the CaR inhibits PTHrP production by MMECs but stimulates PTHrP production by Comma-D cells (immortalized murine mammary cells) and MCF-7 human breast cancer cells. We found that changes in intracellular cAMP, but not phospholipase C or MAPK signaling, correlated with the opposing effects of the CaR on PTHrP production. Pharmacologic stimulation of cAMP accumulation increased PTHrP production by normal and transformed breast cells. Inhibition of protein kinase A activity mimicked the effects of CaR activation on inhibiting PTHrP secretion by MMECs and blocked the effects of the CaR on stimulating PTHrP production in Comma-D and MCF-7 cells. We found that the CaR coupled to Galphai in MMECs but coupled to Galphas in Comma-D and MCF-7 cells. Thus, the opposing effects of the CaR on PTHrP production are because of alternate G-protein coupling of the receptor in normal versus transformed breast cells. Because PTHrP contributes to hypercalcemia and bone metastases, switching of G-protein usage by the CaR may contribute to the pathogenesis of breast cancer.

Extracellular calcium-sensing receptor in rat oligodendrocytes: Expression and potential role in regulation of cellular proliferation and an outward K+ channel

A G protein-coupled, extracellular calcium (Ca(0)2+)-sensing receptor (CaR) cloned from parathyroid, kidney, and brain plays crucial roles in systemic calcium metabolism. In brain, the CaR is located in nerve terminals as well as in fiber tracts, where it may be expressed in glia. Moreover, there is Ca2+- and K+-dependent communication between axons and oligodendroglia. To investigate further the potential role of the CaR in oligodendroglia, we studied expression of CaR mRNA and protein as well as the effects of CaR agonists on cellular proliferation and Ca2+-activated K+ channel activity in immature rat oligodendrocytes in primary culture. Reverse transcriptase polymerase chain reaction and sequencing of CaR transcripts from oligodendrocytes revealed >99% sequence identity with the rat kidney CaR. Northern analysis demonstrated 7.5 and 4.1 kb transcripts in oligodendrocytes, similar to those in rat parathyroid and kidney, while Western analysis and immunocytochemistry with CaR-specific antisera showed the presence of CaR protein. Immunocytochemically, the CaR was colocalized with galactocerebroside in the cultured oligodendrocytes. Raising Ca(0)2+ from 1.8 to 4.8 mM or addition of the polycationic CaR agonist neomycin (300 microM) modestly but significantly increased [3H]-thymidine incorporation into oligodendrocytes. Elevating Ca(0)2+ from 0.75 to 3.0 mM or addition of 100 microM neomycin also produced 2-2.5-fold increases in the open state probability (Po) of an outward K+ channel with a unitary conductance of 88+/-5 pS. Taken together, our data show that the CaR is expressed in immature oligodendrocytes and may be functionally linked to cellular proliferation and an outward K+ channel potentially contributing to local ionic homeostasis in the vicinity of oligodendroglia.

Extracellular calcium‐sensing receptor in rat oligodendrocytes: Expression and potential role in regulation of cellular proliferation and an outward K channel

A G protein-coupled, extracellular calcium (Ca02+)-sensing receptor (CaR) cloned from parathyroid, kidney, and brain plays crucial roles in systemic calcium metabolism. In brain, the CaR is located in nerve terminals as well as in fiber tracts, where it may be expressed in glia. Moreover, there is Ca2+- and K+-dependent communication between axons and oligodendroglia. To investigate further the potential role of the CaR in oligodendroglia, we studied expression of CaR mRNA and protein as well as the effects of CaR agonists on cellular proliferation and Ca2+-activated K+ channel activity in immature rat oligodendrocytes in primary culture. Reverse transcriptase polymerase chain reaction and sequencing of CaR transcripts from oligodendrocytes revealed >99% sequence identity with the rat kidney CaR. Northern analysis demonstrated 7.5 and 4.1 kb transcripts in oligodendrocytes, similar to those in rat parathyroid and kidney, while Western analysis and immunocytochemistry with CaR-specific antisera showed the presence of CaR protein. Immunocytochemically, the CaR was co-localized with galactocerebroside in the cultured oligodendrocytes. Raising Ca02+ from 1.8 to 4.8 mM or addition of the polycationic CaR agonist neomycin (300 μM) modestly but significantly increased [3H]-thymidine incorporation into oligodendrocytes. Elevating Ca02+ from 0.75 to 3.0 mM or addition of 100 μM neomycin also produced 2–2.5-fold increases in the open state probability (PO) of an outward K+ channel with a unitary conductance of 88 ± 5 pS. Taken together, our data show that the CaR is expressed in immature oligodendrocytes and may be functionally linked to cellular proliferation and an outward K+ channel potentially contributing to local ionic homeostasis in the vicinity of oligodendroglia. GLIA 24:449–458, 1998. © 1998 Wiley-Liss, Inc.

Change in blood pressure during altered sodium intake is not associated with calciotropic hormone level.

1. We evaluated the effects of the dietary restriction of sodium chloride on blood pressure and systemic calcium metabolism in 19 in-patients with essential hypertension (11 men and 8 women, mean age 49.9 +/- 12.1 years). 2. All patients received a high-sodium diet (250 mmol/day) for 1 week, followed by a low-sodium diet (10 mmol/day) for another week. Intake of potassium (100 mmol/day) and of calcium (15 mmol/day) were kept constant throughout the study. 3. Sodium restriction significantly reduced the mean blood pressure (from 114.0 +/- 1.9 to 105.0 +/- 13.7 mmHg, P < 0.01). Urinary calcium excretion was significantly reduced (from 5.1 +/- 2.4 to 2.2 +/- 1.0 mmol/day, P < 0.01). 4. The change in mean blood pressure after sodium restriction was not correlated with a change in any parameter of calcium metabolism [whole blood ionized calcium, plasma intact parathyroid hormone, or 1,25-(OH)2 vitamin D3]. 5. Plasma renin activity during a regular sodium diet, an index of renin status, was significantly and inversely correlated with the change in blood pressure during sodium restriction, but not with any change in the parameters of calcium metabolism. 6. We conclude that sodium restriction reduces blood pressure and decreases urinary calcium excretion. However, we observed no significant role of extracellular calcium concentration or of calciotropic hormone concentration in the mechanism of sodium sensitivity.

Disturbed calcium metabolism in offspring of hypertensive parents.

To assess a possible heritability of a disturbed calcium metabolism in relation to blood pressure regulation, 28 young normotensive offspring of either hypertensive or normotensive parents were studied while administered a defined diet with daily sodium chloride of 6 and 20 g/day for 7 days each. Before the high salt diet was begun, the cytosolic calcium concentration ([Ca2+]i) in platelets was elevated in offspring of hypertensive parents, whereas serum electrolytes, plasma renin activity, plasma catecholamines, and 24-hour urinary excretion of sodium and calcium showed no difference between the two groups. On exposure to a high salt diet, the mean blood pressure increased (from 80 +/- 2 to 85 +/- 2 mm Hg, p less than 0.05) in offspring of hypertensive parents. These changes in mean blood pressure were positively correlated with the basal platelet [Ca2+]i (r = 0.61, p less than 0.01), whereas [Ca2+]i did not demonstrate any significant changes. When the subjects were administered the high salt diet, plasma ionized calcium decreased (from 2.37 to 2.21 meq/l, p less than 0.05) and 1,25-dihydroxyvitamin D3 increased (from 32.7 to 40.8 pg/ml, p less than 0.05) with a transient relative hypercalciuria in offspring of hypertensive parents. This increase of 1,25-dihydroxyvitamin D3 was significantly correlated with the changes in mean blood pressure (r = 0.62, p less than 0.01). Disturbed intraplatelet and systemic calcium metabolism may be of predictive value in the development of hypertension.

Cytosolic free calcium in platelets

Relationships between cytosolic free calcium ([Ca2+]i) in platelets, indices of systemic calcium metabolism and blood pressure were examined in 86 subjects; 29 patients with untreated and 29 patients with treated essential hypertension, six patients with borderline hypertension and 22 healthy reference subjects. In order to analyse interactions between the variables, multivariate statistical analyses were employed. The patients with untreated hypertension had higher [Ca2+]i values in non-activated platelets (P = 0.04) and lower levels of plasma ionized calcium (P = 0.02) than the reference subjects. In multivariate models analysing platelet [Ca2+]i mean blood pressure (MBP), plasma ionized calcium, serum parathyroid hormone (PTH) and body mass index (BMI), the relationship between platelet [Ca2+]i and blood pressure was attenuated (P = 0.13), whereas the inverse relationships between plasma ionized calcium and MBP (P = 0.01) and between platelet [Ca2+]i and serum PTH (P = 0.06) seen in univariate analyses persisted. According to the multivariate models the [Ca2+]i value explained only 5% of the MBP variability. Thus, the data from this investigation do not support a close relationship between basal platelet [Ca2+]i and blood pressure. The inverse relationship between plasma ionized calcium and blood pressure, independent of platelet [Ca2+]i and serum PTH, suggests a direct interaction between plasma ionized calcium and blood pressure regulation.

Clinical studies of calcium metabolism in essential hypertension.

Many factors can ultimately lead to an increased blood pressure and it is a generally accepted view that an increase in the active tension of arterioles reflects an increase of the free calcium concentration in the cytosol of the vascular smooth muscle cells. Only recently, however, has the possibility been considered that blood pressure regulation could be influenced by calcium homeostasis. A background for these studies has been provided by the epidemiological observations which link hypertension to a low dietary intake of calcium as well as experimental studies in animals, mostly rats, which have demonstrated that various disturbances of calcium metabolism are related to a raised blood pressure. This review is focused on clinical studies of a possible association between systemic calcium metabolism and the regulation of blood pressure.

Effect of lead on calcium homeostasis in the isolated rat hepatocyte

The effect of lead intoxication on the cellular metabolism of calcium was studied in the isolated rat hepatocyte in primary cell culture. Hepatocytes were incubated for 20 hr in medium containing 0, 10, 50, or 100 μ m Pb 2+ and 45Ca. The cellular metabolism of calcium was evaluated by kinetic analysis of desaturation curves fit to a three-term polyexponential equation. Lead caused a dose-dependent increase in the size (nmol/mg cell protein) of all three kinetic compartments; however, the most remarkable increase was in the deep (desaturation half-time ∼ 100 min) intracellular compartment which includes mitochondria. The efflux rate constants, desaturation half-times, and fluxes associated with these compartments were also altered in lead-intoxicated hepatocytes. The present study indicates that pertubations in the homeostasis of cellular calcium were not dependent upon alterations in serum calcium or upon the physiological regulators of systemic calcium metabolism, e.g., vitamins and hormones.