【目的】调查浙江省004岁儿童血清维生素A缺乏（vitamin A deficiency,VAD）的流行病学概况及危险因素,为防治VAD提供依据。【方法】采用分层抽样的方法抽取符合条件的儿童,抽取静脉血进行血清维生素A（vi-tamin A）水平的测定,并同时...【目的】调查浙江省004岁儿童血清维生素A缺乏（vitamin A deficiency,VAD）的流行病学概况及危险因素,为防治VAD提供依据。【方法】采用分层抽样的方法抽取符合条件的儿童,抽取静脉血进行血清维生素A（vi-tamin A）水平的测定,并同时请家长填写喂养和家庭状况调查问卷。【结果】共抽取适龄儿童357名,平均血清VA水平为（1.653±0.47）μmol/L,亚临床VA缺乏的发生率为3.08%;1岁以内缺乏的发生率最高,随年龄增加,发生率逐渐下降;不同性别儿童的血清VA水平和VAD的发生率差异无显著性;回归分析发现居住农村、父母教育水平低、不规律口服VA胶丸和年龄小的儿童是VAD的高危人群。【结论】浙江省0-4岁儿童血清VAD的发生率较1998年明显下降,但仍属轻度缺乏的地区,高危因素是儿童年龄小、居住在农村、父母受教育程度低和未口服VA胶丸。展开更多
Objective: To investigate effects of developmental lead exposure on nitric oxide synthase (NOS) activity in different brain regions and on N-methyl-D-aspartate (NMDA) receptor mRNA expression in the hippocampus of rat...Objective: To investigate effects of developmental lead exposure on nitric oxide synthase (NOS) activity in different brain regions and on N-methyl-D-aspartate (NMDA) receptor mRNA expression in the hippocampus of rats. On the basis of these observations, we explored possible mechanisms by which lead exposure leads to impaired learning and memorizing abilities in children. Methods: A series of rat animal models exposed to low levels of lead during the developing period was established (drinking water containing 0.025%, 0.05% and 0.075% lead acetate). NOS activities in the hippocampus, the cerebral cortex, the cerebellum and the brain stem were determined with fluorescence measurement and levels of mRNA expression of the NMDA receptor 2A (NR2A) subunit and NMDA receptor 2B (NR2B) subunit in the rat hippocampus were measured with Retro-translation (RT-PCR). Results: There were no differences in the body weight of rat pups between any of the groups at any given time (P>0.05). The blood lead level of Pb-exposed rat pups showed a systematic pattern of change: at 14 d of age, it was lower than that at 7 d of age, then rising to the peak level at 21 d and finally falling to lower levels at 28 d. The hippocampal NOS activities of lead-exposed groups were all lower than that of the control group on the 21 st and 28th day (P<0.01). NOS activities in the cerebellum of lead-exposed groups were all lower than that of the control group on the 21 st and 28th day (P<0.001) and the NOS activity of the 0.025% group was significantly lower than that of the 0.05% and 0.075% groups on the 28th day (P<0.05).NOS activity in the cerebral cortex of the 0.075% group was significantly lower than that of the control, 0.025% and 0.05% groups on the four day spans (P<0.001). There was no significant difference of NOS activity in the brain stem between any lead-exposed group and the control group on the four day spans. In the 0.05% and the 0.075% groups, the level of NR2A mRNA expression was higher than that in the control group at 7 d and 14 d of age (P<0.05). In the 0.025% group, the level of NR2A was found to be higher than that in the control group at 7 d of age only (P<0.05). No significant differences were found for the levels of NR2B mRNA expression between any of the groups at any given time. Conclusions: NOS activity in the hippocampus, the cerebral cortex and the cerebellum are inhibited by lead exposure. The degree of the inhibitory effect depends on the time span of exposure and the lead concentration. Developmental low-level lead exposure was found to raise the level of NR2A mRNA expression in the hippocampus of rats. Developmental low-level lead exposure does not affect the level of NR2B mRNA expression in the hippocampus.展开更多
文摘【目的】调查浙江省004岁儿童血清维生素A缺乏（vitamin A deficiency,VAD）的流行病学概况及危险因素,为防治VAD提供依据。【方法】采用分层抽样的方法抽取符合条件的儿童,抽取静脉血进行血清维生素A（vi-tamin A）水平的测定,并同时请家长填写喂养和家庭状况调查问卷。【结果】共抽取适龄儿童357名,平均血清VA水平为（1.653±0.47）μmol/L,亚临床VA缺乏的发生率为3.08%;1岁以内缺乏的发生率最高,随年龄增加,发生率逐渐下降;不同性别儿童的血清VA水平和VAD的发生率差异无显著性;回归分析发现居住农村、父母教育水平低、不规律口服VA胶丸和年龄小的儿童是VAD的高危人群。【结论】浙江省0-4岁儿童血清VAD的发生率较1998年明显下降,但仍属轻度缺乏的地区,高危因素是儿童年龄小、居住在农村、父母受教育程度低和未口服VA胶丸。
基金Project (No. 021103009) supported by the Science and Technology Bureau of Zhejiang Province, China
文摘Objective: To investigate effects of developmental lead exposure on nitric oxide synthase (NOS) activity in different brain regions and on N-methyl-D-aspartate (NMDA) receptor mRNA expression in the hippocampus of rats. On the basis of these observations, we explored possible mechanisms by which lead exposure leads to impaired learning and memorizing abilities in children. Methods: A series of rat animal models exposed to low levels of lead during the developing period was established (drinking water containing 0.025%, 0.05% and 0.075% lead acetate). NOS activities in the hippocampus, the cerebral cortex, the cerebellum and the brain stem were determined with fluorescence measurement and levels of mRNA expression of the NMDA receptor 2A (NR2A) subunit and NMDA receptor 2B (NR2B) subunit in the rat hippocampus were measured with Retro-translation (RT-PCR). Results: There were no differences in the body weight of rat pups between any of the groups at any given time (P>0.05). The blood lead level of Pb-exposed rat pups showed a systematic pattern of change: at 14 d of age, it was lower than that at 7 d of age, then rising to the peak level at 21 d and finally falling to lower levels at 28 d. The hippocampal NOS activities of lead-exposed groups were all lower than that of the control group on the 21 st and 28th day (P<0.01). NOS activities in the cerebellum of lead-exposed groups were all lower than that of the control group on the 21 st and 28th day (P<0.001) and the NOS activity of the 0.025% group was significantly lower than that of the 0.05% and 0.075% groups on the 28th day (P<0.05).NOS activity in the cerebral cortex of the 0.075% group was significantly lower than that of the control, 0.025% and 0.05% groups on the four day spans (P<0.001). There was no significant difference of NOS activity in the brain stem between any lead-exposed group and the control group on the four day spans. In the 0.05% and the 0.075% groups, the level of NR2A mRNA expression was higher than that in the control group at 7 d and 14 d of age (P<0.05). In the 0.025% group, the level of NR2A was found to be higher than that in the control group at 7 d of age only (P<0.05). No significant differences were found for the levels of NR2B mRNA expression between any of the groups at any given time. Conclusions: NOS activity in the hippocampus, the cerebral cortex and the cerebellum are inhibited by lead exposure. The degree of the inhibitory effect depends on the time span of exposure and the lead concentration. Developmental low-level lead exposure was found to raise the level of NR2A mRNA expression in the hippocampus of rats. Developmental low-level lead exposure does not affect the level of NR2B mRNA expression in the hippocampus.
