Tsunesuke Shimotsuji

[55] Competitive protein binding assay for plasma 25-hydroxycholecalciferol

Publisher Summary This chapter discusses competitive protein binding assay for plasma 25-hydroxycholecalciferol. The present method was developed in authors laboratory, using a specific 25-hydroxycholecalciferol (25-OH-D 3 ) binding protein from the plasma or kidney cytosol of vitamin D-deficient rat. It has been shown that 25-hydroxycholecalciferol and 25-hydroxyergocalciferol react identically in this assay, such that it can be used for the measurement of 25-hydroxy derivatives of vitamin D2 and vitamin D3. Crystalline 25-OH-D 3 is dissolved in ethanol to give a concentration of 280 μg/ml and stored at –20°. Before using in an assay, an aliquot is serially diluted with ethanol to give several standard solutions with a concentration range of 25-OH-D 3 from 10 ng/50μl to 0.5 ng/50 μl. The intra-assay variation was assessed by extracting five 0.5-ml aliquots of the same plasma sample from a healthy subject and assaying each concentrations of 25-OH-D 3 in one assay. A coefficient of intra-assay variation was 7.7%. The inter-assay variation was estimated by extracting and assaying samples from a healthy subject on six different occasions. A coefficient of inter-assay variation was 11.8%.

Serum calcium regulating hormones in the perinatal period.

SummaryTo clarify perinatal vitamin D metabolism, we measured 25-hydroxyvitamin D (25OHD), 24,25-dihydroxyvitamin D [24,25(OH)2D], 1,25-dihydroxyvitamin D [1,25(OH)2D], calcium (Ca), phosphorus (P), parathyroid hormone (PTH), and human calcitonin (CT) in paired maternal, cord, and infant serum. Cord serum 25OHD was significantly lower than the maternal level, and cord serum 24,25(OH)2D was also significantly below the maternal concentrations. Maternal, cord, and infant serum 1,25(OH)2D, on the other hand, was significantly higher than the normal adult level. The serum PTH was low, but the CT concentration was high in the cord. Cord serum Ca and P levels were significantly higher than maternal. The reason for the elevated circulating 1,25(OH)2D level in the perinatal period is uncertain, and we speculate that the possible factors are gonadal steroids, placental lactogen, prolactin, and CT. In addition, serum 24,25(OH)2D and 1,25(OH)2D concentrations are under some control by the fetus.

Plasma 1,25-dihydroxyvitamin D concentrations in cords, newborns, infants, and children

SummaryPlasma 1,25-dihydroxyvitamin D [1,25-(OH)2-D] was measured in cord serum, newborns, infants, and children. The mean for the values obtained from the six cords was significantly higher than the mean for the older children (6–15 years). The mean for the six newborns (0–1 week) was significantly higher than that for the older children. The mean for the nine infants (1 week-6 months) and the 14 younger children (6 months-6 years) was significantly higher than that for older children. The present study suggests that the perinatal period is associated with a marked increase in 1,25-(OH)2-D.

A specific competitive protein binding assay for serum 24,25-dihydroxyvitamin d in normal children and patients with nephrotic syndrome

A specific competitive protein binding assay for 24,25-dihydroxyvitamin D by Sephadex LH-20 column chromatography, followed by high pressure liquid chromatography with normal rat kidney cytosol as the binding protein, was developed. The mean concentrations of serum 24,25-dihydroxyvitamin D of the cord, in newborn infants and in infants under 12 months of age were 0.90 +/- 0.40 (S.D.) ng/ml, 0.52 +/- 0.21 (S.D.) ng/ml and 1.20 +/- 0.38 (S.D.) ng/ml, respectively. These concentrations were significantly lower than those in children aged 1-15 years (1.96 +/- 0.83 (S.D.) ng/ml). The serum levels in the acute stage of the nephrotic syndrome were significantly reduced, and they increased in remission. These results show that patients wioth nephrotic syndrome have low levels of serum 24,25-dihydroxyvitamin D. This is probably due to its loss in the urine.

The plasma levels of 25-hydroxyvitamin D in patients with various liver diseases and the response of 25-hydroxyvitamin D to vitamin D treatment.

ABSTRACT. The mean plasma levels of 25‐hydroxyvitamin D (25‐OH‐D) were measured before and after the administration of 2000 units of daily oral vitamin D2 for a period of 2 weeks in 9 normal infants and children, 7 infants with neonatal hepatitis and persistent neonatal hepatitis, and 4 infants with congenital biliary atresia. The mean plasma level of 25‐OH‐D increased significantly from 19.5±3.7 (S.E.) ng/ml to 34.0±6.8 (S.E.) ng/ml after administration of vitamin D2 in controls (p<0.05). The mean plasma level of 25‐OH‐D also increased from 8.0±2.1 (S.E.) ng/ml to 22.1±2.6 (S.E.) ng/ml after vitamin D treatment in hepatitis group (p<0.05). In patients with congenital biliary atresia, vitamin D treatment did not affect the plasma levels of 25‐OH‐D.

Vitamin D Metabolism in Hypophosphatemic Vitamin D-Resistant Rickets

Plasma levels of 1,25-(OH)2-D were low in children with hypophosphatemic vitamin D-resistant rickets (HVDRR), but increased after very large doses of 1 alpha-OH-D3. These results suggest that the metabolism of 1,25-(OH)2-D is accelerated in HVDRR. In addition, the lower level of plasma 1,25-(OH)2-D in untreated HVDRR was correlated with the lower level of serum phosphate and renal threshold phosphate concentration (TmP/GFR). The administration of 1 alpha-OH-D3 to the patients with HVDRR could enhance the renal threshold phosphate concentration.

IgG3 deficiency and severity of 2009 pandemic H1N1 influenza

Background:  The severity of the 2009 pandemic H1N1 influenza (H1N1 pdm 09) in immune deficient children is unknown. The aim of the present study was to investigate this in a case of complete IgG3 deficiency complicated by pneumonia and asthma attack.

Serum immunoglobulin G subclass levels and estimated clinical severity caused by possible influenza A (H1N1) pdm 2009 infection

The clinical severity of the 2009 pandemic H1N1 influenza (H1N1 pdm09) was thought to be related to the difference between the amount of viral load and condition of the host immune response. We investigated the role of serum levels of IgG and its subclasses in clinical severity using the data from 45 child inpatients suffering from bronchitis or mild pneumonia caused by possible H1N1 pdm09 (pH1N1 pdm09) infection. After selecting parameters for serum IgG subclasses and logarithmically transformed urinary beta-2 microglobulin/creatinine (b2MG/Cr) values and admission duration, we performed path analysis using a mean covariance structure equation analysis to investigate the relationship between the clinical severity and the foregoing selected parameters. Total path analyses using a Bayesian method revealed that the estimated clinical severity caused by pH1N1 pdm09 was positively associated with maximal respiration rates, admission duration, and log urinary b2MG/Cr levels, whereas negatively associated with serum IgG, IgG1, IgG2, and IgG3 levels, duration of neuraminidase inhibitor therapy in outpatient clinics, and age. Serum IgG and its subclasses (IgG1–IgG3) reduced estimated clinical severity in children with pH1N1 pdm09 infection.

Early therapy with neuraminidase inhibitors for influenza A (H1N1) pdm 2009 infection

Neuraminidase inhibitors have been reported to decrease mortality in patients infected with influenza A (H1N1) pdm 2009 (H1N1 pdm09), but it is not clear whether they are effective againstH1N1pdm09 in apparently healthy children.

Secondary hyperparathyroidism with 1,25-dihydroxyvitamin D deficiency and pseudohypoparathyroidism in childhood: Relationship between plasma 1,25-dihydroxyvitamin D and parathyroid hormone levels and urinary cyclic AMP response to exogenous PTH

In order to clarify the complex interrelationship between serum calcium, 1,25-dihydroxyvitamin D (1,25(OH)2D), and parathyroid hormone (PTH), and the urinary excretion of cyclic AMP (cAMP) in response to exogenous PTH in pseudohypoparathyroidism (PHP) and related diseases, we investigated 3 patients with parathyroid disorders before and after treatment with 1α-hydroxyvitamin D3 (1α-OH-D3).Low plasma 1,25(OH)2D before treatment increased after giving 1α-OH-D3 (0.1 μg/kg/day), where-as high plasma PTH measured by the C-terminal assay (C-PTH) decreased in all 3. No response in urinary cAMP was found before or after treatment in 2 patients with PHP type I, despite the fall of plasma C-PTH. However, in one patient with extremely high plasma C-PTH but normal N-PTH (measured by a homologous radioimmunoassay using 1–34 human PTH), urinary cAMP response to exogenous PTH was increased after treatment with 1α-OH-D3. We suggest that he had pseudopseudohypoparathyroidism (PPHP) with Albrights hereditary osteodystrophy and a partial deficiency of renal 1α-hydroxylase. In this patient secondary hyperparathyroidism is thought to be due to 1,25(OH)2D deficiency, and the decreased responsiveness to exogenous PTH before treatment due to excess PTH occupying renal receptors.