Oxidative stress in newborn erythrocytes

Phenylhydrazine (PHZ) exposure is used to study in vitro red cell aging mechanisms dependent on Hb oxidation. The effect of PHZ on normal neonatal red blood cells was studied in unseparated blood and after separation into light and heavy cells. PHZ caused more extensive morphologic changes in neonatal than in adult red blood cells. PHZ exposure of neonatal cells caused less reduced glutathione depletion than in adult cells. Although we found the same total amount of oxidized Hb in both cells, a well-defined oxidation product of Hb was demonstrated by M?ssbauer spectra only in neonatal cells. This oxidation product was not methemoglobin but a trivalent, high-spin iron compound. All neonatal cell populations were more sensitive to PHZ than were adult ones, as demonstrated by the presence of Heinz bodies at low PHZ concentration, which did not affect adult cells. These studies demonstrate greater sensitivity of neonatal cells to PHZ in all density-separated populations.     

Markers of oxidative stress and antioxidant activity in plasma and erythrocytes in neonatal respiratory distress syndrome

Markers of oxidative stress and antioxidant activity in plasma and erythrocytes were studied for 14 d after birth in infants with neonatal respiratory distress syndrome ( n = 9) and controls ( n = 36). In plasma, the total radical trapping antioxidant capacity and the chain-breaking antioxidants vitamin C, sulfhydryl groups and bilirubin were similar. The differences in uric acid levels were not consistent, but vitamin E levels and vitamin E/total-lipid ratio were lower in the neonatal respiratory distress group ( p < 0.01). In erythrocytes, the antioxidant enzymes glutathione peroxidase, glutathione reductase and superoxide dismutase did not differ postnatally. Indicators of oxidative damage in plasma (sulfhydryl/protein ratio and thiobarbituric acid reactive substances) showed the same postnatal course in both groups and were not influenced by oxygen therapy. In erythrocytes the reduced/oxidized glutathione ratio showed no consistent differences. In conclusion, this study, using erythrocytes and plasma, does not provide convincing evidence of oxidative damage and diminished antioxidant defenses in preterm infants with neonatal respiratory distress syndrome.     

Cellular dehydration and immunoglobulin binding in senescent neonatal erythrocytes

The life span of neonatal erythrocytes (60-80 days) is shorter than that of adult erythrocytes (120 days). We studied neonatal red blood cells separated on stractan density gradients to further characterize the aging process and to explore the possibility that senescence antigens play a role in the destruction of neonatal erythrocytes. Quantitation of membrane proteins 4.1a and 4.1b served as a marker for cell age and confirmed an enrichment for senescent red cells in the most dense layers of the gradients. Despite the shorter life span of neonatal erythrocytes, cord blood contained a larger percentage of very dense, K+-depleted red cells than did adult blood. ATP levels in dense neonatal and adult cells were decreased to 50-80% of normal values for unseparated red cells. Levels of reduced glutathione did not fall with increasing cell density. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of red cell membrane proteins showed increased membrane-associated globin in senescent neonatal cells, but such gels run without reducing agents did not show oxidative protein cross-linking. Membrane bound immunoglobulins were detected on senescent neonatal and adult red cells by the rosetting antiglobulin test. We conclude that senescence antigens are revealed during the aging process of neonatal erythrocytes, thereby labeling them for antibody-mediated destruction in the reticuloendothelial system.     

Effect of vitamin K1 on glucose-6-phosphate dehydrogenase deficient neonatal erythrocytes in vitro

AIM: To determine whether vitamin K1, which is routinely administered to neonates, could act as an exogenous oxidising agent and be partly responsible for haemolysis in glucose-6-phosphat-dehydrogenase (G-6-PD). METHODS: G-6-PD deficient (n = 7) and control (n = 10) umbilical cord blood red blood cells were incubated in vitro with a vitamin K1 preparation (Konakion). Two concentrations of Vitamin K1 were used, both higher than that of expected serum concentrations, following routine injection of 1 mg vitamin K1. Concentrations of reduced glutathione (GSH) and methaemoglobin, indicators of oxidative red blood cell damage, were determined before and after incubation, and the mean percentage change from baseline calculated. RESULTS: Values (mean (SD)) for GSH, at baseline, and after incubation with vitamin K1 at concentrations of 44 and 444 microM, respectively, and percentage change from baseline (mean (SD)) were 1.97 + 0.31 mumol/g haemoglobin, 1.89 +/- 0.44 mumol/g (-4.3 +/- 13.1%), and 1.69 +/- 0.41 mumol/g (-14.5 +/- 9.3%) for the G-6-PD deficient red blood cells, and 2.27 +/- 0.31 mumol/g haemoglobin, 2.09 +/- 0.56 mumol/g (-7.2 +/- 23.2%), and 2.12 +/- 0.38 mumol/g (-6.0 + 14.1%) for the control cells. For methaemoglobin (percentage of total haemoglobin), the corresponding values were 2.01 +/- 0.53%, 1.93 +/- 0.37% (-0.6 +/- 17.4%) and 2.06 +/- 0.43% (5.7 +/- 14.2%) for the G-6-PD deficient red blood cells, and 1.56 +/- 0.74%, 1.70 +/- 0.78% (12.7 +/- 21.9%), and 1.78 +/- 0.71% (20.6 +/- 26.8%) for the control red blood cells. None of the corresponding percentage changes from baseline was significantly different when G-6-PD deficient and control red blood cells were compared. CONCLUSIONS: These findings suggest that G-6-PD deficient red blood cells are not at increased risk of oxidative damage from vitamin K1.     

Pharmacokinetics and safety of a new solution of vitamin K1(20) in children with cholestasis.

In cholestatic diseases, the absorption of fat-soluble compounds, including vitamin K1(20), is low and periodic administration of vitamin K1(20) is often necessary. Due to the low absorption of vitamin K1(20) from the Konakion formulation, late hemorrhagic disease of the newborn also occurs especially after oral vitamin K1(20) prophylaxis with Konakion. We investigated the pharmacokinetics and the safety of a new formulation of vitamin K1(20) in a mixed micelles (MM) solution. Compared to the old formulation (Konakion) using Cremophor EL as a solubilizer, the higher vitamin K1(20) levels (as measured by HPLC) in serum obtained after oral administration of the MM formulation clearly demonstrate a superiority of this new formulation. Additionally, the elimination of Cremophor EL as well as of propylene glycol from the formulation avoids possible adverse effects associated with intravenous or intramuscular administration. Furthermore, in most cases, the discomfort of parenteral injections can be overcome by simple oral administration even in children with severe cholestasis.     

The effect of hyperoxic exposure on antioxidant enzyme activities of alveolar type II cells in neonatal and adult rats.

Neonatal animals of several species are more tolerant of hyperoxic exposure than are adults, but the mechanisms of increased neonatal tolerance are unknown, as are the cell types, if any, that contribute to oxygen resistance. We studied the effect of in vivo exposure to 85% oxygen for 72 h on the activities of the antioxidant enzymes, glutathione peroxidase, catalase and superoxide dismutase (SOD), in alveolar type II cells and whole lung from adult and neonatal rats. Baseline antioxidant enzyme activities were generally lower in neonatal type II cells compared with adults. Baseline enzyme activities did not differ in neonatal type II cells and lung homogenates except for lower catalase activity in type II cells. Hyperoxic exposure resulted in 35-38% increases in antioxidant enzyme activities in neonatal whole lung. In neonatal type II cells, SOD activity increased by 170% after hyperoxia, whereas catalase and glutathione peroxidase were not significantly changed. In the adult whole lung, hyperoxic exposure resulted in increases in only glutathione peroxidase activity, whereas in adult type II cells there was a significant decrease in SOD activity after O2 exposure. Therefore, although baseline antioxidant enzyme activities were not higher in neonatal type II cells compared with whole lung, there were differences in the antioxidant enzyme responses of adult and neonatal type II cells to hyperoxia, particularly with respect to SOD. The ability of the neonatal type II cell to respond to hyperoxia with an early increase in SOD activity may contribute to the enhanced oxygen tolerance of the neonate.     

Developmental patterns of antioxidant defense mechanisms in human erythrocytes

To obtain a profile of erythrocyte antioxidant defense potential during late fetal development, we studied selected antioxidant parameters in blood samples from 65 neonates with birth wt between 520 and 4210 g and from 12 healthy adults. Erythrocyte superoxide dismutase activity did not change significantly with maturation and no significant differences were observed among preterm infants grouped in increasing birth wt categories, term neonates, and adults. Erythrocyte catalase and glutathione peroxidase, as well as plasma vitamin E levels, showed highly significant positive correlations (p less than 0.001) with increasing fetal wt and gestational age; by term, CAT activity reached a level similar to the adult control group, but glutathione peroxidase activity, as well as plasma vitamin E levels, were markedly lower in all the preterm and in the term groups than in adults (p less than 0.01). Erythrocyte glutathione S-transferase activity showed a negative correlation with increasing gestational age (p less than 0.01) and the adult values were considerably lower than any of the neonatal levels (p less than 0.001). The role of glutathione S-transferase in erythrocyte metabolism remains obscure. Maturational changes in the activity of the red cell enzymes that were studied and in the plasma vitamin E level were apparent from about 31-36 wk of gestation, suggesting that the stimulation for these changes may have commenced from about 28-31 wk.     

A novel inhaled organic nitrate that affects pulmonary vascular tone in a piglet model of hypoxia-induced pulmonary hypertension

Persistent pulmonary hypertension of the newborn is characterized by elevated pulmonary vascular resistance after birth leading to right-to-left shunting and systemic arterial hypoxemia. Inhaled nitric oxide (NO) is effective in reducing the need for extracorporeal membrane oxygenation, but it has potential toxicities, especially in an oxygen-rich environment. A number of other NO-based molecules have been given by inhalation, but their structure-function relationships have not been established. Recent studies have raised the idea that toxic and beneficial properties can be separated. We synthesized a novel organic nitrate [ethyl nitrate (ENO2)], tested it in vitro, and administered it to hypoxic piglets. ENO2 lowered pulmonary artery pressure and raised the Po2 in arterial blood but did not alter systemic vascular resistance or methemoglobin levels. In addition, we tested the effect of ENO2 in the presence of the thiol glutathione, both in vivo and in vitro, and found its action to be enhanced. Although ENO2 is less potent than inhaled NO on a dose-equivalency basis, pretreatment of hypoxic animals with glutathione, which may be depleted in injured lungs, led to a markedly enhanced effect (largely mitigating the difference in potency). These results suggest that ENO2 may hold promise as a safe alternative to NO, particularly in hypoxemic conditions characterized by thiol depletion.     

Oxidative stress is not enhanced in non-malnourished infants with persistent diarrhea.

Increased concentrations of reactive oxygen species (ROS) and depleted antioxidant defences have been implicated in a cycle of infection, malabsorption and malnutrition, leading to persistent diarrhea. In order to determine whether in non-malnourished children oxidative stress predisposes to the development of persistent diarrhea, infants with acute diarrhea (< 7 days) (n = 39) were compared to infants with persistent diarrhea (> 14 days) (n = 38). Lipid peroxidation was assessed by the TBARs assay and expressed as malondialdehyde equivalent content (nmol MDA/ml plasma), and levels of plasma antioxidants vitamin A and vitamin E were determined. In infants with acute and persistent diarrhea nutritional status, as assessed by weight/height and height-for-age, hemoglobin levels, serum albumin and immunoglobulin levels, did not differ between groups. Serum vitamin A and vitamin E levels did not differ in infants with acute or persistent diarrhea. TBARs, expressed as nmol MDA/ml plasma did not differ between infants with acute or persistent diarrhea and furthermore did not differ from levels in a healthy, similar age, control group. Non-malnourished infants with persistent diarrhea do not exhibit plasma antioxidant depletion or enhanced lipid peroxidation. In these infants, oxidative stress, as reflected in plasma, does not play a role in the pathogenesis of persistent diarrhea.     

The responses of glutathione and antioxidant enzymes to hyperoxia in developing lung

Total glutathione levels and the activity of enzymes associated with antioxidant protection in neonatal lung are increased in response to hyperoxia. Glutathione levels in developing rat lung decreased from 24 nmol/mg protein on day 19 of gestation to approximately 12 nmol/mg protein at birth. The initial decrease in glutathione may be due to emergence of other antioxidant systems. Newborn rats placed in 100% oxygen showed a rapid and sustained increase in total glutathione levels which was primarily due to an increase in reduced glutathione. Explants obtained from 16-wk gestation human fetal lung or from 17- to 18-day fetal rat lung also showed increased total and reduced glutathione when cultured in 95% oxygen, 5% CO2 as compared with explants cultured in room air. Type II cells isolated from neonatal rats maintained in oxygen for 6 days also showed glutathione levels twice those found in cells isolated from animals in room air. The activity of antioxidant enzymes (glucose-6-phosphate dehydrogenase, glutathione peroxidase, glutathione reductase) was increased in lungs of newborn rats exposed to 100% oxygen either at birth or 2 days of age. Antioxidant enzyme activity of lung explants cultured in 95% oxygen, 5% CO2 was also higher than in explants maintained in room air. These results suggest that the increases in glutathione and of antioxidant enzymes in vivo and in vitro are a direct effect of oxygen exposure in lung and that the increase of both glutathione and antioxidant enzyme activity is intrinsic to the lung cell itself. It is likely that increases in glutathione in lung represent an important protective mechanism against oxidant injury.     

Effect of hyperoxia on antioxidants in neonatal rat type II cells in vitro and in vivo

Relative resistance to oxygen toxicity in newborn animals (compared to adults) has been associated with increased antioxidant enzymes and glutathione in lung homogenate. The cell type(s) involved in this increase is unknown. We investigated the effect of hyperoxia in vitro and in vivo on the following antioxidants (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, and glutathione) in alveolar type II cells from neonatal rats. Type II cells were exposed to 95% oxygen or air for 48 h in vitro. When expressed per microgram DNA, all the antioxidants except catalase increased during in vitro incubation; only glucose-6-phosphate dehydrogenase and glutathione increased when expressed per mg protein. None of the antioxidants was higher in oxygen-exposed cells than in air-exposed cells. Neonatal rats were exposed to 100% oxygen or air in vivo for 4 d before determination of antioxidants in lung homogenate supernatant and alveolar type II cells. Catalase, glutathione peroxidase, and glutathione reductase were higher but glucose-6-phosphate dehydrogenase and glutathione were lower in type II cells than in lung homogenate from control animals. Alveolar type II cell glucose-6-phosphate dehydrogenase and glutathione were increased but catalase and glutathione reductase were decreased by exposure to hyperoxia. We conclude that the oxygen-induced increase in whole lung antioxidants is not explained by alveolar type II cell hypertrophy or increased antioxidants within type II cells during hyperoxia.     

Decrease in the antioxidant capacity of red blood cells in children with celiac disease.

The erythrocyte glutathione metabolism of 11 children with acute celiac disease (CD), 11 children under gluten free diet with CD and 5 children with cow's milk allergy was compared to that of 11 children with nutritive iron deficiency and to 22 healthy children as controls. Erythrocyte glutathione (GSH) content of celiac children was elevated and the glutathione disulfide (GSSG) level was significantly decreased as compared to normal controls. Erythrocyte GSSG/GSH ratio in acute CD differed also from the one in iron deficiency. In vitro oxidative load of acetylphenylhydrazine proved the impaired glutathione stability of the erythrocytes in acute CD and cow's milk allergy. A parallel rise of methemoglobin and hemichrome level of blood cells was seen. Further on, the selenium content of the red blood cells of CD patients decreased. All alterations of the erythrocyte tended to normalize during the dietetic period. These data suggest a reduced protective capacity of erythrocytes in CD and in cow's milk allergy in childhood against oxidizing stresses.     

Erythrocyte membrane lipid peroxidation before and after vitamin E supplementation in children with cholestasis

In 10 children with chronic cholestasis and without neurologic signs, we evaluated lipid peroxidation and vitamin E levels in serum and in the erythrocytes before and after a therapeutic trial with alpha-tocopherol. We also studied the effects of vitamin E administration on hematocrit and hemoglobin values and on reticulocyte and erythrocyte counts. Plasma and erythrocyte malonyldialdehyde (MDA) values were significantly higher compared with normal control values, whereas plasma and erythrocyte tocopherol measurements were lower. Oral administration of high doses of vitamin E (300 mg/day for 15 days) resulted in lower serum MDA levels, whereas serum vitamin levels did not change significantly. In erythrocytes, the MDA decreased but not to control levels, and vitamin E increased but to lower values than normal. Hematologic values also improved. We conclude that longer treatment might be necessary to completely reverse the oxidative damage associated with vitamin E deficiency in children with cholestasis.     

Compensatory antioxidant activity in blood of women whose pregnancy is complicated by cigarette smoking

In pregnancy complicated by the cigarette smoking the risk of oxidative damage depends not only on the amount of physiologically enhanced free oxygen species but may be affected by intoxication with tobacco smoke radicals. In the presented studies oxidative damage was estimated through measurement of lipid peroxidation, level of total antioxidant activity and selected antioxidants in plasma and erythrocytes of non-smoking and smoking pregnant women. No differences were found between those two groups in the level of lipid peroxidation and antioxidant activity. Plasma concentration of vitamin A was lower by 15% in smoking than in non-smoking women but vitamin E level did not change. In erythrocytes of the smoking group, concentration of reduced glutathione was 35% higher than in the non-smoking group but activity of glutathione peroxidase and concentration of vitamin E were the same. The observed changes indicate that protection of erythrocytes against free radicals may be sufficient to prevent lipid peroxidation and may manifest local and adaptive response of metabolism for tobacco smoking by pregnant women.     

Vitamin K1 levels and K1-dependent coagulation factors II and X in preterm and small-for-date neonates

In 17 preterm neonates and 7 small-for-date neonates, all formula-fed, vitamin K-dependent coagulation factors II and X remained near 45% of adult values from the moment of birth until 28 days postnatally. Vitamin K₁ levels, however, showed a remarkable rise from below the detection limit of 0.022 ng/ml in umbilical cord blood, to serum levels with a range of 0.99–7.29 ng/ml vitamin K₁ on day 3, with a further rise on days 7 and 28 postnatally. Vitamin K₁ (Konakion) parenterally given to a third group of four preterm neonates as a 1 mg dose resulted in very high serum levels of vitamin K₁ (64.08–157.10 ng/ml), but without any significant increase in plasma levels of vitamin K-dependent coagulation factors II and X, compared to the group without any extra vitamin K₁. It is concluded that in healthy preterm and small-for-date neonates no correlation is seen between serum levels of vitamin K₁ and plasma levels of coagulation factors II and X. After administration of 1 mg Konakion no accelerated increase is seen in coagulatin factor activities.     

Maternal-neonatal serum vitamin A concentrations

Prevention of neonatal vitamin A deficiency is related to the adequacy of maternal vitamin A stores. In this study we investigated maternal and cord serum vitamin A and retinol-binding protein (RBP) values in an Indian population including, for the first time, clinically vitamin A-deficient mothers. Twenty-eight maternal-neonatal pairs were selected from maternal cohorts of high socioeconomic status without clinical evidence of vitamin A deficiency (group I) and low socioeconomic status with conjunctival xerosis and Bitot's spots (group II). Maternal education, caloric and vitamin A intakes, weight, height, hemoglobin, and birth weight were significantly lower in group II. Serum vitamin A levels were significantly higher in group I mothers and newborns as were RBP levels in group I mothers. However, a significant difference between groups I and II in cord blood RBP was not observed. Upon correlation of maternal vitamin A levels with cord blood vitamin A levels, a logarithmic relationship was revealed, suggesting saturable transplacental transport of vitamin A.     

Prevention of vitamin K deficiency bleeding with oral mixed micellar phylloquinone: results of a 6-year surveillance in Switzerland

In 1995, a new form of vitamin K prophylaxis with two oral doses of 2 mg mixed micellar phylloquinone (Konakion MM) on the 1st and 4th day of life was introduced in Switzerland. It was hoped that this new galenic preparation of phylloquinone would protect infants with insufficient or absent bile acid excretion from late vitamin K deficiency bleeding (VKDB). Subsequently, the occurrence of VKDB was monitored prospectively between July 1, 1995 and June 30, 2001 with the help of the Swiss Paediatric Surveillance Unit (SPSU). Over a period of 6 years (475,000 deliveries), there were no cases of early (<24 h of age), one case of classical (2–7 days of life), and 18 cases of late (1–12 weeks) VKDB fulfilling standard case definitions. In 13/18 patients with late VKDB there was pre-existing liver disease and in 4/18 patients, parents had refused prophylaxis. The incidence of late VKDB for infants with completed Konakion MM prophylaxis was 2.31/100,000 (95% CI: 1.16–4.14) and for the entire population 3.79/100,000 (95% CI: 2.24–5.98). There was only one case of late VKDB after complete prophylaxis in an infant without underlying liver disease. Conclusion: two oral doses of 2 mg of a mixed micellar vitamin K preparation failed to abolish VKDB. The recommendations for vitamin K prophylaxis in Switzerland have therefore been changed to include a third dose at 4 weeks of age. Starting on January 1, 2004, the incidence of vitamin K deficiency bleeding will again be monitored prospectively by the Swiss Paediatric Surveillance Unit.Abbreviations CI confidence interval - SPSU Swiss Paediatric Surveillance Unit - VKDB vitamin K deficiency bleeding     

Effect of a vitamin/mineral supplement on children and adults with autism

Background

Vitamin/mineral supplements are among the most commonly used treatments for autism, but the research on their use for treating autism has been limited.

Method

This study is a randomized, double-blind, placebo-controlled three month vitamin/mineral treatment study. The study involved 141 children and adults with autism, and pre and post symptoms of autism were assessed. None of the participants had taken a vitamin/mineral supplement in the two months prior to the start of the study. For a subset of the participants (53 children ages 5-16) pre and post measurements of nutritional and metabolic status were also conducted.

Results

The vitamin/mineral supplement was generally well-tolerated, and individually titrated to optimum benefit. Levels of many vitamins, minerals, and biomarkers improved/increased showing good compliance and absorption. Statistically significant improvements in metabolic status were many including: total sulfate (+17%, p = 0.001), S-adenosylmethionine (SAM; +6%, p = 0.003), reduced glutathione (+17%, p = 0.0008), ratio of oxidized glutathione to reduced glutathione (GSSG:GSH; -27%, p = 0.002), nitrotyrosine (-29%, p = 0.004), ATP (+25%, p = 0.000001), NADH (+28%, p = 0.0002), and NADPH (+30%, p = 0.001). Most of these metabolic biomarkers improved to normal or near-normal levels. The supplement group had significantly greater improvements than the placebo group on the Parental Global Impressions-Revised (PGI-R, Average Change, p = 0.008), and on the subscores for Hyperactivity (p = 0.003), Tantrumming (p = 0.009), Overall (p = 0.02), and Receptive Language (p = 0.03). For the other three assessment tools the difference between treatment group and placebo group was not statistically significant. Regression analysis revealed that the degree of improvement on the Average Change of the PGI-R was strongly associated with several biomarkers (adj. R² = 0.61, p < 0.0005) with the initial levels of biotin and vitamin K being the most significant (p < 0.05); both biotin and vitamin K are made by beneficial intestinal flora.

Conclusions

Oral vitamin/mineral supplementation is beneficial in improving the nutritional and metabolic status of children with autism, including improvements in methylation, glutathione, oxidative stress, sulfation, ATP, NADH, and NADPH. The supplement group had significantly greater improvements than did the placebo group on the PGI-R Average Change. This suggests that a vitamin/mineral supplement is a reasonable adjunct therapy to consider for most children and adults with autism.

Trial Registration

Clinical Trial Registration Number: NCT01225198     

Shift of serum osteocalcin components between cord blood and blood at day 5 of life

Vitamin K deficiency is a relatively common condition in neonates. However, the role of vitamin K in neonatal bone metabolism remains to be determined. Osteocalcin (OC) is the most abundant noncollagenous protein in bone, and is regulated to be gamma-carboxylated by vitamin K. In this study, we measured gamma-carboxylated osteocalcin (Gla-OC) and non- or undercarboxylated osteocalcin (Glu-OC) separately, and examined the effects of vitamin K on osteocalcin metabolism. Eighteen full-term healthy neonates were enrolled in this study. In the cord and d-5 blood samples, the OC levels were determined by three different methods to examine the intact OC by immunoradiometric assay (IRMA), Gla-OC, and Glu-OC. Serum vitamin K fractions, hepaplastin test, and type 1 procollagen carboxyl extension peptide were also determined. Urine samples were also collected from the first voiding and on d 5 to determine urinary pyridinoline, deoxypyridinoline, and gamma-carboxylated glutamic acid. Serum levels of phylloquinone (PK) and menaquinone (MK)-4 increased on d 5 following vitamin K administration and increased intake in breast milk and/or formula. The OC levels determined by IRMA did not change between cord and d-5 blood samples, but the Gla-OC level increased remarkably and Glu-OC reduced to a negligible level. OC in cord blood is mainly Glu-OC, and Glu-OC is replaced with Gla-OC within 5 d of life after vitamin K supplement. The IRMA assay fails to distinguish Gla-OC from Glu-OC and caution is needed to estimate bone turnover with this method in the perinatal period.     

维生素 D 缺乏对子代大鼠肺形态结构及血小板源性生长因子-A 表达的影响

目的：研究孕期维生素 D（VitD）缺乏对子代大鼠肺形态发育及血小板源性生长因子-A（PDGF-A）表达的影响。方法：雌性Sprague-Dawley (SD) 大鼠随机分为对照组、VitD 缺乏模型组（每组6只）。对照组正常饲养;模型组予以避光、不含 VitD 的饲料喂养,2周后与成熟 SD 雄性大鼠交配,每组取孕20 d的胎肺及生后1 d 新生鼠肺,光镜及电镜下观察肺形态结构, RT-PCR 及 Western blot 分别检测肺组织PDGF-A mRNA及蛋白水平的表达。结果：光镜下,模型组子鼠肺泡平均表面积、平均呼吸膜周径均小于对照组（P<0.05）,平均肺泡间隔厚度大于对照组（P<0.05）;电镜下,模型组子鼠的板层小体数量明显少于对照组,成熟细胞器较少见。RT-PCR 及 Western blot结果显示模型组子鼠肺组织PDGF-A mRNA和蛋白表达水平均低于对照组（P<0.05）。结论：孕期 VitD 缺乏抑制孕晚期胎鼠及新生大鼠的肺形态发育。VitD 缺乏能显著抑制肺组织 PDGF-A 表达;PDGF-A表达减低可能是VitD缺乏抑制大鼠肺发育的重要机制之一。