• Nutrition Research and Practice
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• v.9 no.2
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• pp.158-164
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• 2015

BACKGROUND/OBJECTIVES: Vitamin D deficiency is common in hemodialysis patients. The aim of this study was to identify whether or not sun exposure and dietary vitamin D intake have effects on serum 25-hydroxyvitamin D (25(OH)D) status in hemodialysis (HD) patients. The objective was to identify the main determinants of serum vitamin D status in the study subjects. SUBJECTS/METHODS: A cross-sectional study of 47 HD patients (19 males and 28 females) was performed. We assessed serum 25(OH)D and $1,25(OH)_2D$ levels between August and September 2012 and analyzed the prevalence of vitamin D deficiency in HD patients. To evaluate the determinants of serum 25(OH)D levels, we surveyed dietary vitamin D intake, degree of sun exposure, and outdoor activities. To compare biological variables, serum 25(OH)D was stratified as below 15 ng/ml or above 15 ng/ml. RESULTS: Mean 25(OH)D and $1,25(OH)_2D$ levels were $13.5{\pm}5.8ng/ml$ and $20.6{\pm}11.8pg/ml$, respectively. The proportions of serum 25(OH)D deficiency (< 15 ng/ml), insufficiency (15-< 30 ng/ml), and sufficiency (${\geq}30ng/ml$) in subjects were 72.4%, 23.4%, and 4.3%, respectively. Prevalence of vitamin D deficiency in female patients was 78.6%, whereas that in males was 63.2% (P = 0.046). Vitamin D intake and sun exposure time were not significantly different between the two stratified serum 25(OH)D levels. Dietary intake of vitamin D did not contribute to increased serum 25(OH)D levels in HD patients. The main effective factors affecting serum 25(OH)D status were found to be the sun exposure and active outdoor exercise. CONCLUSIONS: Hypovitaminosis D is common in HD patients and is higher in females than in males. Sun exposure is the most important determinant of serum 25(OH)D status in HD patients.

• Korean Journal of Community Nutrition
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• v.20 no.3
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• pp.197-207
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• 2015

Objectives: This study was conducted to investigate the effects of the sources of vitamin D (duration of exposure to sunlight, intake of major food sources for vitamin D or vitamin D supplements) on the serum 25-(OH) $D_3$ levels, and the physical growth of a child. Methods: Subjects were 296 children aged 1 to 5 years who visited S hospital located in Changwon City. Survey data collection was carried out by direct interview method, and the biochemical data were collected using hospital records. Results: The study subjects were divided into three groups according to their levels of serum 25-(OH) $D_3$ (deficient, relatively insufficient, sufficient) and their percentage were 48.3%, 44.3% and 7.4% respectively. The average concentration of serum 25-(OH) $D_3$ was $20.41{\pm}6.55ng/mL$, which was relatively insufficient. The average duration of exposure to sunlight was $58.86{\pm}49.18minutes/day$. A total score of vitamin D major food sources was 46.71 points (full marks 153), and the most frequently consumed food items were milk, eggs, and cheese. Thirty-four percent of the subjects took vitamin D supplements and their dose were $11.96{\mu}g/day$. Three vitamin D sources in sufficient group were higher than deficient or relatively insufficient group significantly. Intake of vitamin D supplements showed positive relation (+) and high explanation power ($R^2=0.288$) on serum 25-(OH) $D_3$ concentration, but intake of vitamin D major food sources (+) and the duration of exposure to sunlight (+) had a low explanation power ($R^2=0.068$). The relations between serum 25-(OH) $D_3$ concentration and physical growth (height and weight) were shown as negative (-), and their explanation powers were low as 7.3% and 5.9% respectively. Conclusions: This study results can be useful when discussing the intake standard of vitamin D and the effective intake method for children. In addition, it will be helpful to build the children's nutrition policy and to plan the nutrition education program to improve the vitamin D status in children.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.16 no.4
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• pp.254-260
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• 2013

Purpose: Recently, vitamin D insufficiency has increased and has been correlated to growth and puberty in children. This study was conducted to find the prevalence of subclinical vitamin D insufficiency and its influence on school-aged children in Korea. Methods: The subjects of this study were 397 children aged 7 to 15 years who had been tested for 25-OH vitamin D3 among the outpatients of the Department of Pediatrics in Eulji General Hospital from March 2007 to February 2011. Data for age, sex, comorbidities, serum 25-OH vitamin D3, height, weight, body mass index (BMI), and sunlight exposure time were collected before and after 3 months of vitamin D administration, retrospectively. Results: Vitamin D insufficiency was present in 343 (86%) of the subjects. In the vitamin D insufficient group, chronological age was $8.96{\pm}1.72$ years, mean height (z-score [z]) was $0.51{\pm}1.26$, mean BMI (z) was $0.81{\pm}2.20$, and bone age was $10.26{\pm}1.75$ years. In the vitamin D sufficient group, chronological age was $9.61{\pm}1.77$ years, mean height (z) was -$0.66{\pm}0.98$, mean BMI (z) was -$0.01{\pm}1.16$, and bone age was $9.44{\pm}2.12$ years. A paired t-test showed that three months after vitamin D administration, the mean 25-OH vitamin D3 level in the insufficient group increased to $24.38{\pm}10.03$ ng/mL and mean BMI (z) decreased to $0.67{\pm}1.06$. Conclusion: In Korean school-aged children, vitamin D insufficiency were relatively higher and may be closely related with higher BMI. Insufficient rise of the level of vitamin D after supplementation suggest the new supplementation guidelines, especially for Korean children.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.337-344
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• 2017

To date, no clear threshold that has been established for defining an adequate store of vitamin D for bone health. Therefore, this study aims to determine the required level of vitamin D to maintain a healthy skeleton based on bone remodelling process among healthy adult population. This was a cross sectional study, involving a healthy adult population in Kota Bharu, Malaysia, aged 18~50 years. We measured serum 25(OH)D (vitamin D), serum parathyroid hormone (PTH), serum C-terminal telopeptide of type 1 collagen (CTX), and Procollagen 1 Intact N-Terminal (P1NP) in 120 healthy adults selected via multi stage sampling (64 males, 56 females) from 6 subdistricts in Kota Bharu. The mean level of 25(OH)D was 23.50 (${\pm}8.74$) nmol/L. There was a significant difference of the vitamin D level between genders ($26.81{\pm}8.3nmol/L$ vs $19.72{\pm}7.68nmol/L$ in males and females respectively) (p value<0.001). More than 50% of female subjects had 25(OH)D less than 20 nmol/L, while only 20.3% of male subjects had 25(OH)D below 20 nmol/L. Based on the LOESS plot, the bone turnover markers showed a plateauing result, at the 25(OH)D level of 35 nmol/L for CTX and 20 nmol/L for P1NP. Contrastingly, PTH showed a step rise in the 25(OH)D level of 20 nmol/L. Based on the LOESS plot for CTX, P1NP and PTH versus 25(OH)D, level of vitamin D between 20 to 35 nmol/L is recommended to maintain healthy skeleton.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.1
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• pp.141-148
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• 1998

This study describes the effects of 1,25-dihydroxyvitamin D3[1,25(OH)2D3, calcitriol] analog, 1,25(OH)2-16ene-23yne-D3 on proliferatin and differentiatin of the human histiocytic lymphoma cell line U937. This paper also describes the effects of 1,25(OH)2-16ene-23yne-D3 on ${\gamma}$-interferon(IFN-${\gamma}$) synthesis by phytohemagglutinin-activated peripheral blood lymphocytes(PBLs). In the present investigation, 1,25(OH2)-16ene-23yne-D3 was compared to the natural metablite of vitamin D3, 1,25(OH)2D3. 1,25(OH)2-16ene-23yne-D3 was more potent than 1,25(OH)2D3 for inhibition of proliferation and induction of differentiation of U937 cells, Its effects on inhibition of proliferation was about 30-fold more potent than 1,25(OH)2D3. On induction of differentiation as measured by nonspecific esterase (NSE) activity and morphologic change, this analog morphologically and functionally differentiated U937 cells to monocyte-macrophage phenotype showing a decrease of N/C ration in Giemsa staining and the increase of adherence ability of surface. After 3 days in culture, a more significant supression of IFN-${\gamma}$ synthesis analog on supression of IFN-${\gamma}$ synthesis was a dose-dependent manner, with peak activity at 10-7M. The strong direct effects of 1,25(OH)2-16ene-23yne-D3 on cell proliferation and cell differentiation, make this compound an interesting candidate for clinical studies for several types of malignancies, and the effects on supression of IFN-${\gamma}$ synthesis provide the further evidence for a role of 1,25(OH)2-16ene-23yne-D3 in immunoregulation.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.106-112
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• 2020

Analyzing vitamin D levels is important for monitoring health conditions because vitamin D deficiency is associated with various diseases such as rickets, osteomalacia, cardiovascular disorders and some cancers. However, vitamin D concentration in the blood is very low with optimal level of 75 nmol/L, making quantitative analysis difficult. The objective of this study was to develop a highly sensitive analysis method for vitamin D using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS). 25-hydroxyvitamin D (25(OH)D), which has been used as an indicator of vitamin D metabolites in human biofluids was chemically derivatized using a secosteroid signal enhancing tag (SecoSET) with powerful dienophile and permanent positive charge. The SecoSET-derivatized 25(OH)D provided good linearity (R² > 0.99) and sensitivity (limit of quantitation: 11.3 fmol). Chemical derivatization of deuterated 25-hydroxyvitamin D₃ (d₆-25(OH)D3) with SecoSET enabled absolute quantitative analysis using MALDI-MS. The highly sensitive method could be successfully applied into monitoring of quantitative changes of bioactive vitamin D metabolites after treatment with ketoconazole to inhibit 1α-hydroxylase reaction related to vitamin D metabolism in human breast cancer cells. Taken together, we developed a MALDI-MS-based platform that could quantitatively analyze vitamin D metabolites from cell products, blood and other biofluids. This platform may be applied to monitor various diseases associated with vitamin D deficiency such as rickets, osteomalacia and breast cancer.

• Clinical and Experimental Reproductive Medicine
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• v.46 no.3
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• pp.132-139
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• 2019

Objective: Vitamin D-binding protein (VDBP) mediates various biological processes in humans. The goal of this study was to investigate whether VDBP gene polymorphisms could predispose Korean women to endometriosis. Methods: We prospectively enrolled women with endometriosis (n = 16) and healthy controls (n = 16). Total serum 25-hydroxyl vitamin D (25(OH)D) concentrations were measured using an Elecsys vitamin D total kit. Levels of bioavailable and free 25(OH)D were calculated. Concentrations of VDBP were measured using a vitamin D BP Quantikine ELISA kit. DNA was extracted using a DNeasy blood & tissue kit. Two single-nucleotide polymorphisms (SNPs; rs4588 and rs7041) in GC, the gene that codes for VDBP, were analyzed using a TaqMan SNP genotyping assay kit. The functional variant of VDBP was determined based on the results of the two SNPs. Results: Gravidity and parity were significantly lower in the endometriosis patients than in the control group, but serum CA-125 levels and the erythrocyte sedimentation rate were significantly higher. Total serum 25(OH)D levels in the endometriosis patients were significantly lower than in the control group. However, serum bioavailable 25(OH)D, free 25(OH)D, and VDBP levels did not differ significantly between the endometriosis and control groups. The genotypes and allele frequencies of GC were similar in both groups. Conclusion: Korean women with endometriosis had lower total serum 25(OH)D concentrations than controls. Neither serum VDBP concentrations nor polymorphisms in the gene coding for VDBP were associated with endometriosis. Further studies are needed to investigate the pathophysiology and clinical implications of 25(OH)D and VDBP in endometriosis.

• Journal of Animal Science and Technology
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• v.56 no.8
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• pp.33.1-33.8
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• 2014

Background: Sox 9 is a major marker of chondrocyte differentiation. When chondrocytes are cultured in vitro they progressively de-differentiate and this is associated with a decline in Sox 9 expression. The active form of vitamin D, 1, 25 $(OH)_2D_3$ has been shown to be protective of cartilage in both humans and animals. In this study equine articular chondrocytes were grown in culture and the effects of 1, 25 $(OH)_2D_3$ upon Sox 9 expression examined. The expression of the transient receptor potential vanilloid (TRPV) ion channels 5 and 6 in equine chondrocytes in vitro, we have previously shown, is inversely correlated with de-differentiation. The expression of these channels in response to 1, 25 $(OH)_2D_3$ administration was therefore also examined. Results: The active form of vitamin D (1, 25 $(OH)_2D_3$ when administered to cultured equine chondrocytes at two different concentrations significantly increased the expression of Sox 9 at both. In contrast 1, 25 $(OH)_2D_3$ had no significant effect upon the expression of either TRPV 5 or 6 at either the protein or the mRNA level. Conclusions: The increased expression of Sox 9, in equine articular chondrocytes in vitro, in response to the active form of vitamin D suggests that this compound could be utilized to inhibit the progressive de-differentiation that is normally observed in these cells. It is also supportive of previous studies indicating that $1{\alpha}$, 25-dihydroxyvitamin $D_3$ can have a protective effect upon cartilage in animals in vivo. The previously observed correlation between the degree of differentiation and the expression levels of TRPV 5/6 had suggested that these ion channels may have a direct involvement in, or be modulated by, the differentiation process in vitro. The data in the present study do not support this.

• Clinical and Experimental Pediatrics
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• v.60 no.8
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• pp.248-253
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• 2017

Purpose: Vitamin D plays a key role in immune function. Vitamin D deficiency may play a role in the pathogenesis of infections, and low levels of circulating vitamin D are strongly associated with infectious diseases. In this study, we aimed to evaluate the effects of low vitamin D levels in cord blood on neonatal sepsis in preterm infants. Methods: One hundred seventeen premature infants with gestational age of <37 weeks were enrolled. In the present study, severe vitamin D deficiency (group 1) was defined as a 25-hydroxyvitamin D (25(OH)D) concentration <5 ng/mL; vitamin D insufficiency (group 2), 25(OH)D concentration ${\geq}5ng/mL$ and <15 ng/mL; and vitamin D sufficiency (group 3), 25(OH)D concentration ${\geq}15ng/mL$. Results: Sixty-three percent of the infants had deficient levels of cord blood vitamin D (group 1), 24% had insufficient levels (group 2), and 13% were found to have sufficient levels (group 3). The rate of neonatal sepsis was higher in group 2 than in groups 1 and 3. Conclusion: There was no significant relationship between the cord blood vitamin D levels and the risk of neonatal sepsis in premature infants.

• Nutrition Research and Practice
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• v.6 no.1
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• pp.86-90
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• 2012

This study assessed the association between vitamin D sufficiency (serum 25(OH)D ${\geq}30ng/mL$) and alcohol consumption using data from the Korea National Health and Nutrition Examination Survey conducted in 2009. The following characteristics were obtained in 7,010 Korean participants ${\geq}19$-years-of-age: serum 25(OH)D level, alcohol consumption (drinking frequency, drinking number of alcoholic beverages on a typical occasion, average daily-alcohol intake), and potential confounders (age, residence, housing status, occupation, total fat and lean mass, smoking, physical activity, history of liver diseases, liver function, and daily intake of energy, protein, and calcium). After adjusting for confounders, vitamin D sufficiency in men was significantly associated with drinking frequency, number of alcoholic drinks consumed, and average daily alcohol intake; odds ratio of 1.21-1.72, 2.17-3.04, and 2.27-3.09, respectively. Increase in the three alcohol drinking-related behaviors was also linearly associated with increase in serum 25(OH)D level in men. By comparison, there was no significant association between alcohol intake and serum 25(OH)D level in women. The positive association between vitamin D sufficiency and alcohol consumption was evident only in Korean men.