Energy cost of activity and exercise in children and adolescents with cystic fibrosis.

In cystic fibrosis (CF), perturbations of total daily energy expenditure (TDEE) may be a major determinant of altered nutrition and growth. Measurement of TDEE is problematic, though the flex-heart rate method (FHRM) provides a close estimation of TDEE, as compared to the cost-prohibitive, gold standard, the double-labeled water method, and permits estimates of the energy cost of daily activities (ECA) above resting energy expenditure (REE). We hypothesize that alterations in ECA affects TDEE in CF. PURPOSE: To measure components of TDEE in adolescents with CF and normal lung function compared with controls, and to determine whether ECA can be improved by diet and exercise. METHODS: Clinically stable CF subjects (aged 9-13, n=12) and age- and gender-matched controls (n=13) had repeated measurements of TDEE by FHRM, REE, and maximal cardiopulmonary exercise testing (CPET) during a 6-week exercise and diet program. RESULTS: While the mean REE was similar in both groups, ECA was significantly lower in CF adolescents as compared to controls (p=0.02). During CPET, maximal exercise in CF was characterized by hyperventilation, which was unrelated to ventilation-perfusion mismatching. There were no changes in REE after dietary intervention. CONCLUSION: ECA in CF adolescents with normal lung function is lower when compared to healthy controls. These findings support the hypothesis that clinically stable patients with CF have inefficient energy metabolism or alternatively conserve energy during activities of daily living.     

补充维生素D预防骨折——随机对照试验汇总分析

背景：对于脊椎以外的骨折而言，补充口服维生素D的预防作用和用量仍无定论。 目的：评估补充维生素D在预防老年髋骨骨折和非脊椎骨折方面的效果。 数据来源：使用MEDLINE、Cochrance对照试验记录（1960～2005年）以及EMBASE（1991-2005年），对英文和非英文文章进行系统回顾。通过与临床专家接触，通过检索美国社会骨和骨矿研究协会提供的参考文献和摘要（1995～2004年）．进一步寻找更多的研究。检索词包括随机对照试验（randomized controlled trial，RCT）、临床对照试验、随机分配、双盲法、维生素D3、维生素D2；25-羟基维生素D、骨折、人类、老年、摔倒和骨密度。 研究选取：纳入的研究仅限于口服补充维生素D（维生素D3、维生素D2、补钙或不补钙）与补钙或安慰剂比较的双盲RCTs。试验于检查髋部骨折或非脊椎骨折的老年人（年龄≥60岁）中进行。数据提取：两位作者根据预先规定独立提取相关数据，其中包括研究质量指标。 数据综合：所有的汇总分析均以随机效应模型为基础。5项有关髋部骨折的RCTs（n=9294）和7项有关非脊椎骨折危险的RCTs（n=9820）符合我们的纳入标准。所有试验均使用了维生素D3。对髋部和非脊椎骨折预防研究的异质性亦进行观察，用低剂量（400IU／d）和高剂量（700～800IU／d）分别合并RCTs后异质性消失。与补钙或安慰剂相比，每天服700～800IU的维生素D可使髋部骨折的相对危险（relative risk，aa）下降26％（3项RCTs共计5572人；RR，0．74；95％可信区间[confidence interval，CI]，0．61～0．88），使非脊椎骨折的相对危险下降23％（5项RCTs共计6098人；RR，0．77；95％CI，0．68～0．87）。每天服400IU的维生素D（2项RCTs共计3722人；髋部骨折RR，1．15；95％CI，0．88～1．50；非脊椎骨折RR，1．03；95％CI，0．86—1．24）未见明显获益。 结论：口服补充维生素D（700～800IU／d）可以降低尚能活动的老人或慈善机构收容的老年人发生髋部骨折和脊椎以外骨折的危险，每天口服400IU维生素D并不足以预防骨折。     

Fetal growth patterns in fetuses of women with pregestational diabetes mellitus.

OBJECTIVE: To assess the effect of glucose control on the rate of growth of fetuses in women with pregestational diabetes mellitus (Types 1 and 2). METHODS: All pregestational diabetic women booked at Mater Mothers' Hospital, Brisbane, Australia, between 1 January 1994 and 31 December 2002, were included. Pregnancies with congenital fetal anomalies, multiple pregnancies, and pregnancies terminated prior to 20 weeks' gestation were excluded. Dating scans were performed before 14 weeks' gestation and serial scans were performed at 18, 24, 28, 32 and 36 weeks. Fetal parameters, including biparietal diameter, femur length and abdominal circumference, were recorded. The daily growth rates for biparietal diameter, femur length, and fetal abdominal area were calculated and compared with those in a low-risk (non-diabetic) population. The growth rates in fetuses of women with satisfactory diabetic control (HbA1c < 6.5%) and unsatisfactory control (HbA1c > or = 6.5%) in the three trimesters were compared. RESULTS: A total of 174 diabetic pregnancies were included and a total of 997 ultrasound scans were performed. The growth rates for fetuses of mothers with diabetes mellitus were significantly higher than for those in the low-risk population. The z-scores for biparietal diameter, femur length, and fetal abdominal area were 0.18, 0.59 and 1.44, respectively. Fetuses of diabetic mothers with high HbA1c in the first trimester had significantly greater fetal abdominal area growth rate than those with normal HbA1c (fetal abdominal area z-score of 1.7 vs. 0.75, P = 0.009). Although the fetal abdominal area z-scores in fetuses of diabetic mothers with high HbA1c in the second or third trimesters were also higher than those with normal HbA1c levels, the differences did not reach statistical significance. Maternal obesity did not influence the fetal growth rate. CONCLUSION: The rate of growth of fetuses of diabetic mothers differs from that of the normal population. Growth acceleration persists until the late third trimester. Moreover, periconceptional glucose control appears to have a significant effect on accelerated growth of the fetal abdominal area.     

The National Summit on Preconception Care: A Summary of Concepts and Recommendations

The Centers for Disease Control and Prevention (CDC) and 35 partner organizations have engaged in developing an agenda for Preconception Health. A summit was held in June 2005 to discuss the current state of knowledge regarding preconception care and convene a select panel to develop recommendations and action steps for improving the health of women, children, and families through advances in clinical care, public health, and community action. A Select Panel on Preconception Care, convened by CDC, deliberated critical related issues and created refined definition of preconception care. The panel also developed a strategic plan with goals, recommendations, and action steps for improving preconception health. The recommendations and action steps are specific to the implementation of health behavior, access, consumer demand, research, and surveillance activities for monitoring and improving the health of women, children and families. The outcome of the deliberations is the CDC publication of detailed recommendations and action steps in the Morbidity and Mortality Weekly Report series, Recommendations and Reports.

     

An analysis of astrocytic cell lines with different abilities to promote axon growth

The adult mammalian central nervous system (CNS) lacks the capacity to support axonal regeneration. There is increasing evidence to suggest that astrocytes, the major glial population in the CNS, may possess both axon-growth promoting and axon-growth inhibitory properties and the latter may contribute to the poor regenerative capacity of the CNS. In order to examine the molecular differences between axon-growth permissive and axon-growth inhibitory astrocytes, a panel of astrocyte cell lines exhibiting a range of axon-growth promoting properties was generated and analysed. No clear correlation was found between the axon-growth promoting properties of these astrocyte cell lines with: (i) the expression of known neurite-outgrowth promoting molecules such as laminin, fibronectin andN-cadherin; (ii) the expression of known inhibitory molecules such tenascin and chondroitin sulphate proteoglycan; (iii) plasminogen activator and plasminogen activator inhibitor activity; and (iv) growth cone collapsing activity. EM studies on aggregates formed from astrocyte cell lines, however, revealed the presence of an abundance of extracellular matrix material associated with the more inhibitory astrocyte cell lines. When matrix deposited by astrocyte cell lines was assessed for axon-growth promoting activity, matrix from permissive lines was found to be a good substrate, whereas matrix from the inhibitory astrocyte lines was a poor substrate for neuritic growth. Our findings, taken together, suggest that the functional differences between the permissive and the inhibitory astrocyte cell lines reside largely with the ECM.