Estimation of Iron Physiological Requirement in Chinese Children using Single Stable Isotope Tracer Technique

OBJECTIVE

This study is to obtain precise data on iron physiological requirements in Chinese children using single stable isotope tracer technique.

METHODS

Thirty boys (10.6 ± 0.2 years) and 27 girls (10.4 ± 0.2 years) were received oral 6 mg ⁵⁷Fe each day for 5 consecutive days. Venous blood samples were subsequently drawn to examine the change of total iron concentration and ⁵⁷Fe abundance at day 0, 14, 28, 60, 90, 180, 360, 450, 540, 630, 720. The iron physiological requirement was calculated by iron loss combined with iron circulation rate once ⁵⁷Fe abundance stabilized in human body.

RESULTS

The iron physiological requirement was significantly lower in boys than those values in girls (16.88 ± 7.12 vs. 18.40 ± 8.81 μg/kg per day, P < 0.05). Correspondingly, the values were calculated as 722.46 ± 8.43 μg/day for boys and 708.40 ± 7.55 μg/day for girls, respectively. Considering nearly 10% iron absorption rate, the estimated average iron physiological requirement was 6.0 mg/day in boys and 6.2 mg/day in girls.

CONCLUSION

This study indicate that iron physiological requirement could require more daily iron intake in girls as compare with the values in boys having the same body weight. These findings would be facilitate to the new revised dietary reference intakes.

Basal Energy Expenditure of Chinese Healthy Adults: Comparison of Measured and Predicted Values

OBJECTIVE

This study aimed to measure the basal energy expenditure (BEE) of Chinese healthy adults and establish an accurate predictive equation for this population.

METHODS

In total, 470 Chinese healthy adults had their BEE measured using the Cosmed K4b ² portable metabolic system. Multiple linear regression analysis was applied to develop new optimal equations for predicting BEE. The bias, accuracy rate, concordance correlation coefficient (CCC), and root mean square error (RMSE) were used to evaluate the accuracy of the predictive equations.

RESULTS

There was a significant difference in BEE between males and females, with 5,954 kJ/d and 5,089 kJ/d, respectively. People living in rural areas expended significantly higher BEE (5,885 kJ/d) than those in urban areas (5,279 kJ/d). Previous equations developed by Henry, Schofield, Harris-Benedict (H-B), and Liu overestimated the BEE of Chinese healthy adults. The new equations derived from the present study displayed the smallest average bias and RMSE from the measured basal energy expenditure (mBEE). The CCC of the new equations was higher than other predictive equations, but it was lower than 0.8. There was no significant difference in the accuracy rate among all predictive equations.

CONCLUSIONS

Sex and regional differences in BEE were observed in Chinese healthy adults. Neither the widely used previous predictive equations nor the one derived in the present study were accurate enough for estimating the BEE of Chinese healthy adults. Further study is required to develop more accurate equations for predicting the BEE of Chinese healthy adults aged between 20-45 years.

Distribution of High-sensitivity C-reactive Protein Status in an Urban Population in China

OBJECTIVES

To evaluate the distribution by age and sex of serum high-sensitivity C-reactive protein (hsCRP) in an urban Chinese population and to provide a profile prediction for the risk of bacterial infection, inflammatory diseases, or tissue damages in the body.

METHODS

Serum hsCRP was determined using the Roche Tina-quant immuno-turbidimetric assay on a Hitachi 7600-010 automatic biochemical analyzer (Roche Diagnostics) in 1,572 males and 1,800 females, including 78 pregnant women, who were derived from the National Health and Nutrition Survey in 2010-2012.

RESULTS

The average hsCRP concentration in urban China was 0.68 mg/L for males and 0.65 mg/L for females. Significant differences in hsCRP were found among different age groups ( P < 0.05). Monitoring results showed no significant differences among the 6-11, 45-59, and ≥ 60-year-old groups in the comparison of hsCRP between males and females in large cities. However, hsCRP concentration was significantly higher in men aged 12-17 and 18-44 years than in women.

CONCLUSION

The distribution of the hsCRP status of residents in large cities in China was influenced by age and gender, and the hsCRP levels of both sexes increased gradually with age. In addition, hsCRP concentration was higher in healthy pregnant women than in non-pregnant women. Basing on our results, we recommend that this parameter be included in future national and international screening for early detection of various illnesses.

Evaluation of Erythrocyte Iron Incorporation in Beijing Prepubertal Children Using a Single Stable Isotope Tracer Method

OBJECTIVE

To analyze the rate of erythrocyte iron incorporation and provided guidance for the iron nutrition for prepubertal children.

METHODS

Fifty-seven prepubertal children of Beijing were involved in this study and each subject was orally administered 3 mg of ⁵⁷Fe twice daily to obtain a total of 30 mg ⁵⁷Fe after a 5-d period. The stable isotope ratios in RBCs were determined in 14th day, 28th day, 60th day, and 90th day. The erythrocyte incorporation rate in children was calculated using the stable isotope ratios, blood volume and body iron mass.

RESULTS

The percentage of erythrocyte ⁵⁷Fe incorporation increased starting 14 th day, reached a peak at 60 d (boys: 19.67% ± 0.56%, girls: 21.33% ± 0.59%) and then decreased. The erythrocyte incorporation rates of ⁵⁷Fe obtained for girls in 60th day was significantly higher than those obtained for boys ( P < 0.0001).

CONCLUSIONS

The oral administration of ⁵⁷Fe to children can be used to obtain erythrocyte iron incorporation within 90 d. Prepubertal girls should begin to increase the intake of iron and further studies should pay more attention to the iron status in prepubertal children.

[The vitamin D nutritional status in Chinese urban women of child-bearing age from 2010 to 2012]

Objective: To evaluate the vitamin D nutritional status in Chinese women of child-bearing age by analyzing serum 25-hydroxyvitamin D level in 2010-2012. Methods: Data were obtained from the China Nutrition and Health Survey in 2010-2012. Using cluster sampling and proportional stratified random sampling, 1 514 women of child-bearing age (18-44 years old) from 34 metropolis and 41 small and medium-sized cities were included in this study. Demographic information was collected by questionnaire and serum 25-hydroxyvitamin D concentration was determined by radioimmunoassay, in accordance with the 2010 Institute of Medicine of the National Academies standards. We compared differences in vitamin D levels, specifically serious deficiency, lack of deficiency, insufficiency, and excess. Results: The overall serum 25-hydroxyvitamin D level of Chinese urban women of child-bearing age (P(50) (P(25)-P(75))) was 20.1 (15.1-26.3) ng/ml; minorities had a significantly higher serum 25-hydroxyvitamin D level of 22.0 (15.9-27.5) ng/ml compared with women of Han nationality (19.8 (14.9-26.2) ng/ml) (χ(2)=7.02, P=0.008). The proportions of women with serious deficiency, lack of deficiency, insufficiency, and excess vitamin D were 11.6% (n=175), 37.9% (n=574), 35.1% (n=531), and 0.3% (n=5), respectively. Only 15.1% (n=229) of women of child-bearing age had normal vitamin D nutritional status. No significant differences in vitamin D nutritional status were observed according to age, body mass index, city, nationality, educational level, marital status, or household income per capita (P>0.05). Conclusion: Most Chinese urban women of child-bearing age have poor vitamin D levels and require vitamin D supplementation.

Zinc Absorption from Representative Diet in a Chinese Elderly Population Using Stable Isotope Technique

OBJECTIVE

To determine the dietary zinc absorption in a Chinese elderly population and provide the basic data for the setting of zinc (Zn) recommended nutrient intakes (RNI) for Chinese elderly people.

METHODS

A total of 24 elderly people were recruited for this study and were administered oral doses of 3 mg 67Zn and 1.2 mg dysprosium on the fourth day. The primary macronutrients, energy, and phytic acid in the representative diet were examined based on the Chinese National Standard Methods. Fecal samples were collected during the experimental period and analyzed for zinc content, 67Zn isotope ratio, and dysprosium content.

RESULTS

The mean (± SD) zinc intake from the representative Chinese diet was 10.6 ± 1.5 mg/d. The phytic acid-to-zinc molar ratio in the diet was 6.4. The absorption rate of 67Zn was 27.9% ± 9.2%. The RNI of zinc, which were calculated by the absorption rate in elderly men and women, were 10.4 and 9.2 mg/d, respectively.

CONCLUSION

This study got the dietary Zn absorption in a Chinese elderly population. We found that Zn absorption was higher in elderly men than in elderly women. The current RNI in elderly female is lower than our finding, which indicates that more attention is needed regarding elderly females' zinc status and health.

[Study on vitamin A nutritional status of 6- to 17-year-old urban children and adolescents between 2010 and 2012 in China]

Objective: To investigate the vitamin A nutritional status of 6- to 17-year-old urban children and adolescents by analyzing serum retinol level, between 2010 and 2012 in China. Methods: Data were obtained from the China Nutrition and Health Survey in 2010-2012. Using multi-stage stratified sampling and the population proportional stratified random sampling method, 6 617 children aged 6-17 years from 32 metropolis and 41 middle-sized and small cities of China were selected. The questionnaire survey was used to collect demographic information. Blood samples were analyzed using high-performance liquid chromatography to determine serum retinol concentration, and the World Health Organization guidelines were used to evaluate the nutritional status of vitamin A. Vitamin A levels, vitamin A deficiency, and marginal vitamin A deficiency in children with different characteristics were compared. Results: A total of 3 785 cases with valid samples were obtained. The overall mean serum retinol concentration level was (1.49±0.71) μmol/L; the mean serum retinol concentration was (1.55±0.69) μmol/L for metropolis and (1.49±0.75) μmol/L for middle-sized and small cities (P>0.05). The mean serum retinol concentration was (1.52±0.78) μmol/L for boys and (1.47±0.68) μmol/L for girls (P>0.05). The mean serum retinol concentration level was (1.46±0.70) μmol/L for 6- to 11-year-old children and (1.54±0.65) μmol/L for 12- to 17-year-old children (P<0.05). The total vitamin A deficiency rate and marginal vitamin A deficiency rate was 7.69% (291/3 785) and 18.57% (703/3 785), respectively. The vitamin A deficiency rate was 8.00% (36/450) for metropolis and 7.64% (65/3 335) for middle-sized and small cities; 8.12% (155/1 908) for boys and 7.25% (136/1 877) for girls; and 8.04% (171/2 115) for 6- to 11-year-old children and 7.18% (120/1 670) for 12- to 17-year-old children. No significant differences were observed for region, sex, or age (P>0.05). The marginal vitamin A deficiency rate was 19.11% (86/450) for metropolis and 18.50% (617/3 335) for middle-sized and small cities; 18.19% (347/1 908) for boys and 18.97% (356/1 877) for girls, with no significant differences observed (P>0.05). The marginal vitamin A deficiency rate was 16.54% (350/2 115) for 6- to 11-year-old children and 21.13% (353/1 670) for 12- to 17-year-old children (P<0.05). Conclusion: The vitamin A nutritional status of 6- to 17-year-old Chinese urban children and adolescents between 2010 and 2012 has improved, and the gap between cities is narrowing. However, vitamin A deficiency overall remains high, especially in younger children, and requires specific attention.

Protein requirements in healthy adults: a meta-analysis of nitrogen balance studies

OBJECTIVE

The goal of this study was to analyze protein requirements in healthy adults through a meta-analysis of nitrogen balance studies.

METHODS

A comprehensive search for nitrogen balance studies of healthy adults published up to October 2012 was performed, each study were reviewed, and data were abstracted. The studies were first evaluated for heterogeneity. The average protein requirements were analyzed by using the individual data of each included studies. Study site climate, age, sex, and dietary protein source were compared.

RESULTS

Data for 348 subjects were gathered from 28 nitrogen balance studies. The natural logarithm of requirement for 348 individuals had a normal distribution with a mean of 4.66. The estimated average requirement was the exponentiation of the mean of the log requirement, 105.64 mg N/kg•d. No significant differences between adult age, source of dietary protein were observed. But there was significant difference between sex and the climate of the study site (P<0.05).

CONCLUSION

The estimated average requirement and recommended nutrient intake of the healthy adult population was 105.64 mg N/kg•d (0.66 g high quality protein/kg•d) and 132.05 mg N/kg•d (0.83 g high quality protein/kg•d), respectively.

Evaluation of the protein requirement in Chinese young adults using the indicator amino acid oxidation technique

OBJECTIVE

To accurately calculate the protein requirements in Chinese young adults using the indicator amino acid oxidation technique.

METHODS

Nine women and ten men received a restricted daily level of protein intake (0.75, 0.82, 0.89, 0.97, and 1.05 g/kg), along with L-[1-13C]-leucine. Subjects' protein requirement was determined by a biphasic linear regression crossover analysis of F13CO2 data. In doing so, a breakpoint at the minimal rate of appearance of 13CO2 expiration specific to each level of dietary protein was identified. This trial was registered with the Chinese clinical trial registry as ChiCTR-ONC-11001407.

RESULTS

The Estimated Average Requirement (EAR) and the Recommended Nutrient Intake (RNI) of protein for healthy Chinese young adults were determined to be 0.87 and 0.98 g/(kg•d), respectively, based on the indicator amino acid oxidation technique.

CONCLUSION

The EAR and RNI of mixed protein are 5% and 16% that are lower than the current proposed EAR and RNI (0.92 and 1.16 g/(kg•d), respectively), as determined by the nitrogen balance method. The respective EAR and RNI recommendations of 0.87 and 0.98 g/(kg•d) of mixed protein are estimated to be reasonable and suitable for Chinese young adults.

Total energy expenditure of 16 Chinese young men measured by the doubly labeled water method

OBJECTIVE

Doubly labeled water (DLW) method is the gold standard for measuring total energy expenditure (TEE). We used this method to measure TEE in Chinese young men.

METHODS

Sixteen healthy young men age 23±1 years with body mass index 22.0±1.4 kg/m2 were recruited. TEE was measured by the DLW method, and basal energy expenditure (BEE) was determined by indirect calorimetry. We also conducted 24-h activity, energy balance and factorial approach to estimate energy requirements of the subjects.

RESULTS

TEE of subjects by DLW method was 9.45±0.57 MJ/day (2258±180 kcal/day). The 24-h activity was 10.80±0.33 MJ/day (2582±136 kcal/day). The energy requirement, derived from energy balance observations, was 9.93±1.32 MJ/day (2373±315 kcal/day). The BEE of 6.65±0.28 MJ/day (1589±67 kcal/day), calculated by the adjusted Schofield equation, was significantly higher (P<0.001) than that measured by indirect calorimetry, 5.99±0.66 MJ/day (1433±158 kcal/day). The TEE derived from the factorial approach was 10.31±0.43 MJ/day (2463±104 kcal/day).

CONCLUSION

The TEE of Chinese young men measured by the DLW method was about 10% lower than the current recommended nutrient intake (RNI), suggesting that the RNI for Chinese men maybe overestimated. Further studies are warranted to determine the value of the estimated energy requirement.

Assignment of Pdnp2, the gene encoding phosphodiesterase I/nucleotide pyrophosphatase 2, to mouse chromosome 15D2

We have isolated cDNA and genomic DNA encoding mouse PDNP2 (PD-Ialpha). The mouse Pdnp2 cDNA contains a 2,589-nucleotide open reading frame encoding a polypeptide of 863 amino acids. The 5' region of the mouse Pdnp2 gene contains Sp1, Max1, HNF-3B, and AP1 putative transcription factor binding sites, without typical TATA or CAAT boxes. Fluorescence in situ hybridization showed that Pdnp2 is located at Chromosome 15D2, as expected based on mouse-human conserved regions.

Novel SH3 protein encoded by the AF3p21 gene is fused to the mixed lineage leukemia protein in a therapy-related leukemia with t(3;11) (p21;q23)

The mixed lineage leukemia (MLL) gene located at chromosome band 11q23 is frequently rearranged in patients with therapy-related acute monocytic leukemia who received topoisomerase II inhibitors. We have identified a novel fusion partner of MLL (FAB M5b) in a patient who developed t-AML 9 years after treatment for acute lymphoblastic leukemia (ALL). The leukemic cells had a sole karyotypic abnormality of t(3;11) (p21;q23). Screening of a genomic DNA library, prepared from leukemic cell DNA, identified rearranged clones composed of MLL and a novel gene on chromosome 3p21 (AF3p21). The AF3p21 gene encodes a protein of 722 amino acids, which contains an Src homology 3 (SH3) domain, a proline-rich domain, and a bipartite nuclear localizing signal (NLS). RNA analysis demonstrated that exon 6 of the MLL gene fused to exon 2 of the AF3p21 gene. The resulting chimeric protein consists of AT-hooks, methyltransferase, and transcription repressor domains of MLL in addition to the AF3p21 proline-rich domain and NLS but not the AF3p21 SH3 domain.

Genomic structure and promoter analysis of the ecto-phosphodiesterase I gene (PDNP3) expressed in glial cells

PDNP (phosphodiesterase I/nucleotide pyrophosphatase) is one of a series of ectoenzymes that are involved in hydrolysis of extracellular nucleotides. PDNP possesses ATPase (EC 3.6.1.3) and ATP pyrophosphatase (EC 3.6.1.8) activities. Mammalian PDNP consists of three closely related family proteins (PDNP1, -2, and -3), and they are expressed in different cell types and at different developmental stages. Rat PDNP3 is expressed in a subset of immature glial cells and in the alimentary tract. Human PDNP3 is expressed in glioma cells, prostate, and uterus, but not in the alimentary tract. We have cloned genomic DNA containing the whole coding region of the human PDNP3 gene and determined its exon-intron structure. The human PDNP3 gene spans over 60 kb and is organized into 25 exons and 24 introns. We determined the nucleotide sequence of the 5'-flanking region of human and rat PDNP3 genes. The upstream region of both species lacks a canonical TATA box and contains a putative binding site for CCAAT enhancer-binding proteins near the transcription start site. Promoter activity analysis of the 5'-flanking region revealed that the sequence around the CCAAT box is required for its transcriptional activity in 9L rat glioma cells. A gel shift assay demonstrated that 9L nuclear extract contains proteins that bind to this region.

Biochemical and morphological changes in the lenses of selenium and/or vitamin E deficient rats

The activities of glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), superoxide dismutase (SOD) and the contents of malondialdehyde (MDA) and free radicals were measured, and the morphological changes were observed in the lens of control rats, selenium-deficient (SeD) and/or vitamin E deficient (VED) rats. The activities of GSH-Px in the lens of SeD rats decreased significantly. The GSH-Px activities of lens were positively related to erythrocytes selenium level. There was a free radical at g = 2.0015 in the rat lens of all groups, but the content of free radicals in the lens of SeD group was significantly higher than that of the control group. The free radical content of lens was negatively related to erythrocytes selenium level, as well as the GSH-Px activities in the lens. In vitro, ultraviolet radiation caused the generation of another kind of free radical (g = 2.0097) in the lens of all groups, but the amount of the free radical in the lens of the SeD group was also significantly higher than that of the control group. The activities of SOD and GSSG-R in VED rat lens were significantly decreased. The amount of MDA in the lens of SeD and/or VED rats were significantly increased. The results showed that the decrease of antioxidative capability in the lenses of SeD and/or VED rats accelerated the lipid peroxidation and generation of free radicals. Although only early morphological changes in SeD and/or VED rat lens were observed, it is considered that selenium and vitamin E deficiency may be involved in the occurrence of cataract.

Effect of selenium deficiency on tissue taurine concentration and urinary taurine excretion in the rat

The purpose of this study was to determine the effect of selenium deficiency on tissue taurine levels and urinary taurine excretion. Weanling male Sprague-Dawley rats were fed selenium-deficient or selenium-adequate diets for 20 weeks. As selenium deficiency developed, urinary taurine excretion increased in selenium-deficient rats compared to controls. At 12 weeks, the selenium-deficient rats excreted 1.7-fold more taurine than control rats. At the same time plasma glutathione peroxidase was 1.2% of control and plasma glutathione was 226% of control. At 20 weeks, renal taurine was decreased but renal glutathione was increased in selenium-deficient rats compared to controls. Feeding the experimental diet for 6 weeks without methionine supplementation caused a fall in urinary taurine excretion. However, there was no difference between selenium-deficient and control rats. These results indicate that selenium deficiency affects renal handling of taurine in the rat when dietary sulfur amino acids are not restricted.