血清维生素D水平与老年2型糖尿病患者合并认知障碍的关系研究

目的：探讨血清维生素D水平与老年2型糖尿病患者合并认知障碍的关系。方法：收集2021年1月—2022年1月在我院就诊的90例老年糖尿病患者为研究对象。收集老年人性别、年龄、受教育年限、吸烟史、饮酒史、身高、体重、体育活动情况等一般信息及实验室血清25羟维生素D₃[25(OH)D₃]水平检测数据。采用简易智力状态检查(MMSE)量表对患者认知状况进行评估,将患者分为认知正常组和轻度认知障碍组(MCI),分析血清维生素D水平与MCI间的关系。结果：90例老年2型糖尿病患者中,28例发生MCI,发生率为31.11%。男性血清25(OH)D₃水平为(25.82±6.32)ng/mL,维生素D缺乏率合计为15.21%;女性血清25(OH)D₃水平为(24.09±7.92)ng/mL,维生素D缺乏率合计为18.18%,女性血清25(OH)D₃水平显著低于男性(P<0.05)。血清维生素D水平与患者MMSE得分之间呈正相关,年龄、性别、体重过轻、空腹血糖过高、HbA1c过高、血清维生素...     

维生素D营养状况与儿童支气管肺炎发生及转归的关系研究

目的：探讨维生素D营养状况与儿童支气管肺炎发生及临床转归的关系。方法：收集2020年9月—2022年10月在我院儿科收治的123例支气管肺炎患儿和同期154例健康体检健康儿童为研究对象。收集两组儿童一般情况、身高、体重等信息，检测两组儿童血清25(OH)D₃水平，收集支气管肺炎患儿的临床转归情况。采用Spearson相关分析维生素D营养状况与支气管肺炎发生及临床转归的相关性，维生素D营养状况对支气管肺炎发生的影响采用多元Logistic回归分析。结果：支气管肺炎组患儿血清25(OH)D₃水平显著低于正常组儿童[(18.36±2.42)vs(20.92±2.65)] ng/mL，且维生素D不足/缺乏发生率高于正常组组[(45/78) vs(24/130),P<0.05]，且血清25(OH)D₃水平与支气管肺炎的发生呈显著负相关(r=-0.603, P<0.05)。户外活动时间≥2h及维生素D补充是发生支气管肺炎的保护因素(OR<1, P<0.05)，而维生素D不足/缺乏是支气管肺炎的危险因素(OR&...     

维生素D与儿童肺炎支原体肺炎的相关性及辅助治疗效果

目的：探讨维生素D与儿童肺炎支原体感染的相关性，以及维生素D辅助治疗对临床疗效的影响。方法：收集2020年6月—2022年6月在我院儿科收治的72例肺炎支原体肺炎患儿为研究对象，同期纳入问诊就诊的80例非肺炎儿童为正常对照组。检测2组患儿检测血清25(OH)D₃水平，比较两组患儿血清25(OH)D₃水平差异，以及与肺炎支原体感染的相关性。接着将72例肺炎支原体肺炎患儿随机分为观察组和对照组各36例，对照组采用临床常规治疗和护理，观察组患儿在此基础上给予维生素D辅助治疗，比较2组患儿疗效，临床咳嗽、发烧、肺部啰音症状，以及住院时间的差异。结果：肺炎支原体肺炎组患儿血清25(OH)D₃水平显著低于正常组患儿[(18.03±2.36) vs (21.02±2.02) ng/mL](P<0.05)，且肺炎组患者维生素D缺乏和不足率显著高于正常组(P<0.05)，血清肺炎支原体感染与血清25(OH)D₃水平呈反比(r=0.728, P<0.05)。维生素D辅助治疗临床疗效显著优于对照组(P&...     

乙肝病毒感染孕妇维生素D营养状况与妊娠结局的关系研究

目的：探讨乙肝病毒感染孕妇维生素D营养状况变化，以及维生素D营养状况对产妇、新生儿妊娠结局的影响。方法：选取2019年8月—2022年10月在首都医科大学附属北京佑安医院产科定期产检及住院生产的150例诊断为患有乙肝感染的孕妇为研究对象，收集同期在本院就诊分娩的98例正常孕妇为对照组。抽取孕妇住院期间清晨空腹静脉血，观察并记录各维生素D营养状况组乙肝感染孕妇妊娠结局，比较对照组和乙肝感染组孕妇血清25(OH)D₃水平差异，以及乙肝感染孕妇不同维生素D营养状况组产妇和新生儿妊娠结局的差异。结果：乙肝感染组孕妇血清25(OH)D₃水平显著低于正常对照组孕妇[(24.63±2.36) vs (28.84±2.38)ng/mL,P<0.05],且乙肝感染组孕妇维生素D缺乏和不足发生率显著高于对照组[(127/150) vs (49/98),P<0.05]。乙肝感染孕妇中，随着维生素D营养状况的恶化，产妇妊娠期糖尿病、妊娠期高血压，以及新生儿发生早产和新生儿窒息发生率显著增高(P<0.05)。结论：乙肝病毒感染孕妇维生素D营养状况较差...     

维生素D改善肥胖大鼠的脂代谢

本文研究维生素D改善肥胖大鼠脂代谢的作用。建立肥胖大鼠模型,正常组、模型组、高剂量组(2.40μg/mL)、中剂量组(1.20μg/mL)、低剂量组(0.60μg/mL)、奥利司他组(0.10 mg/mL)。统计体重、体长、Lee’s指数、附睾脂肪垫质量、脂肪体重指数,检测总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C),观察大鼠脂肪细胞形态学,检测过氧化物酶体增殖物激活受体γ(PPAR-γ)、瘦素、线粒体解偶联蛋白(UCP)蛋白表达。高剂量组大鼠体重250.76 g、Lee’s指数2.52%、附睾脂肪垫质量5.05 g、脂肪体重指数1.41 g、TC 1.96 mmol/L、TG 0.83 mmol/L、LDL-C 1.05 mmol/L低于模型组大鼠,HDL-C 0.59mmol/L高于模型组大鼠(p0.05)。高剂量组大鼠PPAR-γ、瘦素蛋白表达低于模型组大鼠,高剂量组大鼠UCP蛋白表达高于模型组大鼠(p0.05)。维生素D通过调控PPAR-γ、瘦素、UCP蛋白表达,改善大鼠脂代谢。     

早产儿维生素D营养状况及活性维生素D补充对骨代谢的影响

目的：分析早产儿维生素D营养状况,探索活性维生素D补充对早产儿骨代谢指标的影响。方法：收集我院2020年7月—2021年12月出生的80例28～37 w早产儿和80例同期出生的足月儿为研究对象,留取脐带血检测血清骨钙素(OC)、25-羟维生素D₃[25(OH)D₃]、碱性磷酸酶(ALP)、钙和磷水平,80例早产儿予以维生素D补充,于出生28 d后复查血清25(OH)D₃、OC、ALP、钙和磷水平。分析早产儿维生素D营养状况,比较28 d后早产儿血清维生素D水平变化和骨代谢指标变化情况。结果：早产儿胎龄更短,剖宫产比例更高,且婴儿体重、身高、头围更小。早产儿血清25(OH)D₃平均水平显著低于对照组(P<0.05),且早产儿维生素D缺乏率也显著高于正常新生儿(32/80 vs 12/80,P<0.05)。活性维生素D补充可显著提高早产儿血清25(OH)D₃、OC及ALP。结论：早产儿体格发育不良,维生素D缺乏率较高,活性维生素D补充可改善骨代谢指标,进而促进早产儿骨骼...     

学龄儿童维生素D水平与矿物元素相关性分析

目的:了解广西学龄儿童维生素D(VD)营养状况与矿物元素含量关系,为防治儿童微量营养素缺乏提供科学依据。方法:采用随机整群抽样方法,抽取广西融水县1所中心小学512名6—14岁儿童,采集静脉血,用酶联免疫吸附法测定血清25-羟维生素D[25-(OH)D]浓度,测量身高、体重,计算体质指数(BMI),测定全血铜(Cu)、锌(Zn)、钙(Ca)、铁(Fe)、镁(Mg)元素含量。结果:研究对象血清25-(OH)D平均浓度为22.86±9.37ng/mL,存在男女性别间差异(P0.05)。血清25-(OH)D水平、Cu、Zn、Fe在各年龄组间差异有统计学意义(P0.05),Ca、Mg含量差异不明显(P0.05)。血清25-(OH)D水平与全血钙或铁含量呈负相关(P0.01);与全血镁含量呈正相关(P0.01);与全血铜或锌含量关系不明显(P0.05)。血清25-(OH)D水平与BMI相关性无显著性意义(P0.05),男生BMI高于女生(P0.05)。维生素D缺乏率随年龄增长呈下降趋势(P0.05)。各年龄组钙、铁、锌缺乏率差异不明显(P0.05)。结论:维生素D营养状况与全血钙、铁、镁含量关系密切,儿童维生素D水平受年龄和性别影响,应定期监测,以保障儿童健康成长。     

血清维生素D水平与产后抑郁症的关系研究

目的：分析血清维生素D水平与产后抑郁症的相关性。方法：收集2020年3月—2021年12月在芜湖市第四人民医院门诊就诊的50例首次诊断为产后抑郁症的患者和同期收集的50例正常产后女性为研究对象。产后抑郁症的诊断依据为爱丁堡产后抑郁量表(EP-DS),将得分>13分的女性记为病例组。采用自制问卷收集患者一般情况信息,包括年龄、文化水平、职业、家庭收入情况、睡眠情况及体育活动情况等。收集2组患者清晨空腹静脉血,采用化学发光法检测血清25(OH)D₃水平,酶联免疫吸附法检测血清白细胞介素-6(IL-6)水平。比较产后抑郁症患者与正常女性血清维生素D水平和IL-6水平的差异,分析产后抑郁症的可能危险因素,以及维生素D与产后抑郁症的相关性。结果：2组研究对象年龄、文化水平、职业、家庭月收入间无差异(P>0.05),而患有产后抑郁症的产妇存在睡眠障碍者更多,且更规律体育锻炼更缺乏(P<0.05)。患有产后抑郁症的女性血清维生素D水平显著低于对照组患者[(25.03±4.38) vs (32.04±5.21)ng/mL,P<0.05],而血清IL-6水平...     

鉴定活性维生素D细胞模型的构建

本文构建了维生素D受体(Vitamin D receptor,VDR)融合蛋白的真核表达载体,并获得稳定表达VDR融合蛋白的细胞体系,为含有活性维生素D食品及药物的鉴定建立成熟的细胞模型。设计并合成特异性引物扩增VDR基因,将扩增产物克隆至pcDNA3.1/His真核表达载体上,将其转染HEK293细胞。采用免疫沉淀(IP)技术鉴定VDR融合蛋白的表达效率。在构建pcDNA 3.1/VDR-His成功的基础上,用活性1,25(OH)_2D_3处理转染的细胞,收集总蛋白和m RNA,分别利用免疫印迹(Western blot,WB)和实时定量PCR(q RT-PCR)技术,检测VDR融合蛋白以及其下游基因CYP24A1基因的表达。IP结果证实VDR融合蛋白具有转录活性。WB和q RT-PCR结果显示,1 nmol/L浓度的活性1,25(OH)_2D_3处理转染细胞能有效激活VDR蛋白的表达,以及显著增强CYP24A1的m RNA表达(p0.01)。利用该细胞模型检测维生素D类药物的活性,结果显示不同药物中维生素D的活性与药物种类有关。pcDNA3.1/VDR-His融合表达载体构建成功,并以此构建了鉴定活性维生素D的细胞模型。     

维生素A通过铁调节蛋白2基因表达来影响铁代谢

目的：通过大鼠原代肝细胞培养(体外试验)来研究维生素A通过铁调节蛋白2(IRP-2)来影响铁代谢。方法：将SD大鼠原代分离肝细胞(seglent法),随机分组严重缺乏A、边缘缺乏B、常规组C、预防治疗组D、RO阻抑组E,分别给予0、0.5、1.0、50μmol/L全反式视黄酸和50μmol/L全反式视黄酸+10μmol/L RO(RARα阻断剂)培养4 d。用RT-PCR法测量肝脏的IRP-2 mRNA的情况。结果：大鼠维生素A缺乏时,原代肝细胞表达IPR-2 mRNA水平增强(P<0.05),补充维生素A后,IPR-2 mRNA表达下降,但加入RO后,维生素A这种作用明显减弱了。结论：维生素A作为转录调节剂,可通过结合视黄酸细胞核受体(RARα),改变IRP-2转录水平,改变铁调节稳态,调节机体贫血状态。     

维生素D3补充对大鼠免疫细胞功能影响的实验研究

目的：维生素D（VD）对机体免疫功能作用已引起广泛关注,本实验研究补充不同剂量VD,对大鼠免疫细胞活性的影响。方法：将30只Wistar大鼠随机分为3组,分别为VD,1（对照组）、VD,2和VD,3组,每组10只,雌雄各半。VD,l组大鼠每天摄入VD,20IU／kg（生理剂量,相当于成人每天摄入5txg维生素D,）、VD2组和VD3组分别补充200IU／（kg·d）（10倍量）和1000IU／（kg·d）（50倍量）的VD,;补充时间为4周。实验结束时麻醉无痛处死,取血样（约5mL）离心,采用LC-Ms／MS测定血清VD,浓度、CCK-8法检测淋巴细胞增殖活性、流式细胞术测单核细胞吞噬功能。结果：经过4周VD,补充后,结果显示,VD,1、VD,2和VD。3组大鼠血清VD,浓度分别为14．8ng／mL、34．7n【g／mL和60．7ng／mL,随着补充剂量的增加,机体VD,吸收水平也显著提高;VDl补充后,VD,2组淋巴细胞增殖活性的OD值达到3．04,明显高于VD,1组的2．64（P〈0．05）,但VD33组与VD31组相比淋巴细胞增殖活性无显著性差异（P〉0．05）。采用流式细胞术观察单核细胞吞噬活性（荧光强度）,结果显示VD,2组大鼠单核细胞吞噬活性荧光强度到达19．98,明显高于VD,1组的15．48,而高剂量VD,补充的VD,3组大鼠单核细胞吞噬活性未见明显增强。结论：适宜剂量VD,[200IU／（kg·d）]补充可增强淋巴细胞增殖和单核细胞吞噬活性,而过高剂量（50倍生理剂量）未观察到明显免疫调节作用。     

VA和VD对结核病患者结核杆菌耐药性的实验研究

目的：评价维生素A（VA）和维生素D（VD）对结核杆菌的抑菌活性及其与耐药性的关系。方法：选择2012年2.5月期间就诊于某胸科医院的118例痰培养结果为阳性的结核病患者为研究对象,从痰液中分离并培养出阳性菌株,采用绝对浓度法进行药物敏感试验;将不同浓度vA和VD添加到改良罗氏培养基中,制成实验培养基,并以单纯的改良罗氏培养基为对照接种实验菌株,培养3-4周后,观察菌落生长状况。结果：与对照组相比,添加500IU／mL（VAl）、1000Iu／mL（VA2）和2000IU／mL（VA3）维生素A的各剂量组培养基上的结核杆菌生长都受到不同程度的抑制,菌落生长结果为阳性所占的比例分别为92．37％、81．36％和86．44％,均低于对照组的100％,差异具有统计学意义（P〈0．05）;添加25IU／mL（VDl组）、50IU／mL（VD2组）、75IU／mL（VD3组）和100IU／mL（VD4组）维生素D的各剂量组菌落生长结果为阳性所占的比例分别为94．07％、93．22％、94．92％和91．53％,与对照组相比差异具有统计学意义（P〈o．05）。随着VA剂量的增加,VA2组培养结果为阴性的比例为18．64％,高于VAl组的7．63％,而阳性（2＋）和阳性（3＋）的比例分别为58．47％和2．54％,均低于VAl组的66．10％和6．87％,抑菌效果有所提高（P〈0．0167）;而VA3组与VA2组相比,抑菌效果增加不明显（P〉0．0167）。VD各剂量组相比,抑菌效果无明显差异（P〉0．05）;VA与VD的抑菌效果相比,VA2组及VA3组的抑菌效果优于VD组（P〈0．05）;结合菌株的药敏试验结果,发现维生素AD对结核杆菌生长的抑制效果与菌株耐药性无关（P〉0．05）。结论：适宜剂量的VA（1000IU／mL）和VD（25IU／mE）能抑制结核杆菌的生长．且与结核杆菌的耐药性无关。     

Vitamin D₂ impairs utilization of vitamin D₃ in high-yielding dairy cows in a cross-over supplementation regimen

Vitamin D exists in 2 forms that are important regarding vitamin D status and supply in cattle: vitamin D₂ (D₂) and vitamin D₃ (D₃). To become physiologically active, both D₂ and D₃ must undergo 25-hydroxylation in the liver. The resulting 25-hydroxyvitamin D₂ [25(OH)D₂] and 25-hydroxyvitamin D₃ [25(OH)D₃] are measured as indicators of the physiological vitamin D status of cattle. The study used 14 Danish Holstein cows housed without access to sunlight. The cows were orally administered 250 mg (1.0 × 10⁷ IU) of D₂ and D₃ in a cross-over design with 2 treatment groups and 2 study periods, rendering 4 treatments when carryover effects were taken into account: D₂ given first, D₂ given last after D₃, D₃ given first, and D₃ given last after D₂. Two weeks elapsed between the treatment in the first study period and the treatment in the second study period. Blood samples were collected 0, 3, 6, 14, 17, 20, 23, 26, 40, 48, 70, 94, 166, and 214 h after providing the oral bolus of vitamin to the cows. Comparisons between plasma levels of the metabolites D₂, D₃, 25(OH)D₂, and 25(OH)D₃ over time were made by comparing areas under the plasma concentration curves. Oral administration of D₃ increased plasma D₃ (182.6 ± 17.1 ng/mL; mean ± SEM) and 25(OH)D₃ (103.5 ± 10.0 ng/mL) more efficiently than oral administration of D₂ increased plasma D₂ (49.1 ± 32.6 ng/mL) and 25(OH)D₂ (27.9 ± 2.1 ng/mL). The D₃ given after an oral dose of D₂ was less efficient for increasing plasma concentrations of 25(OH)D₃ (61.2 ± 12.0 ng/mL) compared with D₃ given without previous D₂ administration (103.5 ± 10.0 ng/mL), whereas the plasma concentrations of D₃ itself were the same when given first (182.6 ± 17.1 ng/mL) as when given after D₂ (200.0 ± 123.9 ng/mL). The same occurred for plasma concentrations of D₂ metabolites both if D₂ was given first (49.1 ± 32.6 ng/mL) and after D₃ (54.7 ± 7.7 ng/mL). In conclusion, D₃ given after D₂ is less efficient at increasing the plasma status of 25(OH)D₃ than D₃ given without previous D₂ administration.     

Reduced serum vitamin D concentrations in healthy early-lactation dairy cattle

Cattle obtain vitamin D by ingestion or cutaneous exposure to UV light. Dairy cattle diets are frequently supplemented with vitamin D to compensate for limited sun exposure or during times of increased metabolic demands, such as the periparturient period, to maintain calcium homeostasis. Whether housing and supplemental vitamin D practices supply adequate amounts of vitamin D to optimally support the transition from gestation to lactation in dairy cattle is unknown. Our objective was to determine how serum vitamin D concentrations of dairy cows change with season, age, parity, and stage of lactation. Clinically healthy cows (n = 183) from 5 commercial dairies were enrolled in the study. Serum samples were collected at dry off, within 7 d of entering the close-up group, and within 7 d after calving (calving+7). Vitamin D status was determined by measuring serum 25-hydroxyvitamin D [25(OH)D] by radioimmunoassay. We performed repeated-measures mixed-effects linear regression to determine the effects of season, age, parity, and lactation stage (dry off, close-up, and calving+7) on 25(OH)D concentrations in serum. Bivariable analysis indicated that parity, age, and season were not associated with serum 25(OH)D concentrations. Sample period affected 25(OH)D concentrations, with the highest 25(OH)D levels at dry off (99.7 ± 1.9 ng/mL) followed by close up (93.8 ± 2.1 ng/mL), with the lowest levels at calving+7 (82.6 ± 1.7 ng/mL). These data showed a large depletion of 25(OH)D in dairy cattle postpartum compared with late prepartum, although the biological significance of this change in these healthy cattle is unclear. Consumption of serum 25(OH)D by immune system functions and calcium homeostasis in early lactation likely caused the reduction in serum 25(OH)D concentrations after calving. These results suggest that determining whether serum 25(OH)D concentrations are associated with the incidence of transition period disease is an appropriate next step. Assessing the effects of enhanced vitamin D supplementation of cows in early lactation on postpartum diseases may be warranted.     

香菇多糖脱蛋白工艺及其抗氧化活性研究

采用低共溶剂(deep eutectic solvents,DES)-K2HPO4双水相体系(aqueous two-phase system,ATPS)将香菇多糖水提液中的多糖与蛋白质进行分离萃取,蛋白质富集于DES相,糖类富集于K2HPO4相。综合考察了DES物质的量比、K2HPO4浓度、DES的加入量以及萃取时间对蛋白质脱除率的影响,通过正交试验进一步优化试验条件,得出蛋白质脱除的最优工艺参数:以氯化胆碱/丙三醇(物质的量之比1∶2,2.6 mL)、K2HPO4(0.6 g/mL,3 mL)构建双水相体系,加入2 mL香菇多糖水提液,萃取30 min后,香菇多糖蛋白质的脱除率高达90.8%,香菇多糖回收率为98.0%。在此条件下得到的香菇多糖具有清除DPPH自由基的能力,说明脱蛋白后的香菇多糖具有一定的抗氧化性。     

Vitamin D status and glucose metabolism in youth

This study aimed to review and synthesize the available scientific evidence on the relationship between serum 25(OH)D concentrations and glucose metabolism among adolescents. A total of 19 studies were included. Many studies did not find a relation between 25(OH)D concentrations and insulin sensitivity, but most studies have shown that vitamin D status influences glucose dysregulation in youth due to particularities of this life stage. Considering the prevalence of vitamin D deficiency and insufficiency were high among adolescents, the importance for vitamin D status correction in this young group, in which chronic diseases are not expected but getting every day more common, is mandatory.     

分级醇沉香菇多糖益生活性研究

目的 比较分级醇沉香菇多糖的益生活性差异。方法 采用20%、50%和80%乙醇对香菇多糖进行分级醇沉,并研究分级醇沉香菇多糖对植物乳杆菌的增殖作用和体外耐受模拟胃肠液性能。结果 在发酵48 h时,以80%醇沉香菇多糖为碳源时,植物乳杆菌活菌数可达到9.62 log CFU/mL; 50%醇沉(9.21 log CFU/mL)、20%醇沉(9.07 log CFU/mL)和菊粉组(8.67 log CFU/mL)无显著差异,但都显著高于葡萄糖组的活菌数(8.35 log CFU/mL,P<0.05)。发酵液pH表明,在发酵48 h时, 80%醇沉香菇多糖组的pH降低至3.23,显著低于其他组(P<0.05)。体外模拟胃肠液结果表明,以80%醇沉香菇多糖为碳源培养120 min时,植物乳杆菌在模拟胃液和肠液中的存活率分别为63.37%和96.37%,显著高于葡萄糖组和菊粉组(P<0.05)。结论 以80%醇沉香菇多糖为碳源可以促进植物乳杆菌的增殖,并提高植物乳杆菌在模拟胃肠液环境中的存活率,具有一定的益生元活性。     

25-羟基维生素D检测方法研究进展

维生素D(vitamin D, VD)是人体内一种重要的调节因子,除参与人体内钙磷代谢,其在高血压、心血管疾病、肿瘤及糖尿病等疾病中也扮演着重要角色。25羟基维生素D(25-hydroxy vitamin D, 25(OH)D)是VD在人体内的主要存在形式,性质稳定(半衰期2周),其水平能充分反映食物摄入和自身合成VD总量,在精准药物治疗与营养膳食理念方面具有重要意义,因此,需要高准确测定25(OH)D浓度水平。本文综述了25(OH)D的前处理方法和检测方法,主要包括放射免疫法、酶联免疫吸附法、化学发光免疫测定法、高效液相色谱法和液相色谱-串联质谱法,并展望了其发展趋势。     

Short communication: The preruminant calf as a model for characterizing the effects of vitamin D status in the neonate

The objective of this study was to evaluate the feasibility of using the preruminant dairy calf as a model for evaluating effects of vitamin D status in the neonate. Because the newborn calf can be sustained during the first weeks of life solely on a fluid diet having a defined composition, has documented nutritional requirements, and is minimally affected by repeated samplings of peripheral blood, it has the potential to serve as a model for characterizing nutrient-specific effects on the growth and health of the neonate. Colostrum-fed Holstein bull calves (n = 13) entered the trial at approximately 4 d of age. All calves were fed a custom-formulated milk replacer devoid of vitamin D. Plasma 25-hydroxyvitamin D₃ concentrations in all calves were determined on a regular basis beginning at d 0. Using this information, low- and high-status groups of calves were established by subcutaneous administration of 25-hydroxyvitamin D₃. To maintain targeted plasma 25-hydroxyvitamin D₃ concentrations in low (<30 ng/mL) and high (>60 ng/mL) vitamin D-status calves, low-status calves (n = 6) received a total of 8,600 IU (2,225 IU/wk) of vitamin D during the experimental period and high-status calves (n = 7) received 54,000 IU (13,500 IU/wk). Concentrations of 25-hydroxyvitamin D₃ in low-status calves averaged 27 ng/mL, compared with 78 ng/mL in high-status calves, and were less at all sampling times from d 7 to d 28. Concentrations of 1,25-dihydroxyvitamin D₃ and 25-hydroxyvitamin D₃ were not correlated. Calcium, magnesium, and phosphorous concentrations were unaffected by 25-hydroxyvitamin D₃ administration; however, plasma calcium and 1,25-dihydroxyvitamin D₃ concentrations were correlated. Calcium and magnesium concentrations decreased with age but remained within normal ranges for dairy cattle. These results indicate that it is possible to predictably control vitamin D status over a 28-d period and suggest that the preruminant calf might be useful as a model for studying effects of vitamin D on growth, development, and immune function in the neonate.